WASHINGTON, Dec. 21 — A lengthy investigation of the father of Pakistan's atomic bomb, Abdul Qadeer Khan, by American and European intelligence agencies and international nuclear inspectors has forced Pakistani officials to question his aides and openly confront evidence that the country was the source of crucial technology to enrich uranium for Iran, North Korea and possibly other nations.
Until the past few weeks, Pakistani officials had denied evidence that the A. Q. Khan Research Laboratories, named for the man considered a national hero, had ever been a source of weapons technology to countries aspiring to acquire fissile material. Now they are backing away from those denials, while insisting that there has been no transfer of nuclear technology since President Pervez Musharraf took power four years ago.
Dr. Khan, a metallurgist who was charged with stealing European designs for enriching uranium a quarter century ago, has not yet been questioned. American and European officials say he is the centerpiece of their investigation, but that General Musharraf's government has been reluctant to take him on because of his status and deep ties to the country's military and intelligence services. A senior Pakistani official said in an interview that "any individual who is found associated with anything suspicious would be under investigation," and promised a sweeping inquiry.
Pakistan's role in providing centrifuge designs to Iran, and the possible involvement of Dr. Khan in such a transfer, was reported Sunday by The Washington Post. Other suspected nuclear links between Pakistan and Iran have been reported in previous weeks by other news organizations.
An investigation conducted by The New York Times during the past two months, in Washington, Europe and Pakistan, showed that American and European investigators are interested in what they describe as Iran's purchase of nuclear centrifuge designs from Pakistan 16 years ago, largely to force the Pakistani government to face up to a pattern of clandestine sales by its nuclear engineers and to investigate much more recent transfers.
Those include shipments in the late 1990's to facilities in North Korea that American intelligence agencies are still trying to locate, in hopes of gaining access to them.
New questions about Pakistan's role have also been raised by Libya's decision on Friday to reveal and dismantle its unconventional weapons, including centrifuges and thousands of centrifuge parts. A senior American official said this weekend that Libya had shown visiting American and British intelligence officials "a relatively sophisticated model of centrifuge," which can be used to enrich uranium for bomb fuel.
A senior European diplomat with access to detailed intelligence said Sunday that the Libyan program had "certain common elements" with the Iranian program and with the pattern of technology leakage from Pakistan to Iran. The C.I.A. declined to say over the weekend what country appeared to be Libya's primary source. "It looks like an indirect transfer," said one official. "It will take a while to trace it back."
There are also investigations under way to determine if Pakistani technology has spread elsewhere in the Middle East and Asia, but so far the evidence involves largely the exchange of scientists with countries including Myanmar. There have been no confirmed reports of additional technology transfers, intelligence officials say.
The Pakistani action to question Dr. Khan's associates was prompted by information Iran turned over two months ago to the International Atomic Energy Agency, under pressure to reveal the details of a long-hidden nuclear program. But even before Iran listed its suppliers to the I.A.E.A. — five individuals and a number of companies from around the world — a British expert who accompanied agency inspectors into Iran earlier this year identified Iranian centrifuges as being identical to the early models that the Khan laboratories had modified from European designs. "They were Pak-1's," said one senior official who later joined the investigation, saying that they were transferred to Iran in 1987.
Pakistani officials said the sales to Iran might have occurred in the 1980's during the rule of the last American-backed military ruler, Gen. Mohammad Zia ul-Haq. They acknowledge questioning three scientists: Mohammed Farooq, Yasin Chohan and a man believed to be named Sayeed Ahmad, all close aides to Dr. Khan.
A senior Pakistani intelligence official said Mr. Farooq was in charge of dealing with foreign suppliers at the Khan laboratory, run by Dr. Khan until he was forced into retirement — partly at American insistence — in the spring of 2001. At the laboratory, where much of the work was done that led to Pakistan's successful nuclear tests in 1998 and its deployment of dozens of nuclear weapons, Mr. Chohan was in charge of metallurgical research, according to senior Pakistani officials.
Contacted by telephone last week, relatives of Mr. Farooq said he was still being questioned. Mr. Chohan's family said Sunday that Mr. Chohan had been released and was at home.
Pakistani officials have insisted in that if their scientists and engineers had done anything wrong, it was without government approval. They said their bank accounts and real estate holdings were also being investigated. A senior Bush administration official, while declining to comment on what was learned when Pakistani officials questioned the men, said that all three had been "well known to our intelligence folks." Another official said the United States had steered Pakistani officials to the three, in hopes it would further pressure Dr. Khan.
Dr. Khan declined several requests in November for an interview, routed through his secretary and his official biographer, Zahid Malik. However, Mr. Malik relayed a statement from Dr. Khan that he had never traveled to Iran. "He said, `I have never been there in my life.' " A European confidante of Dr. Khan's, who spoke on the condition of anonymity, said the Pakistani scientist put the blame for transfers on a Middle Eastern businessman who he said was supplying Pakistan with centrifuge parts and, on his own, double-ordered the same components to sell to Iran. "There is evidence he is innocent," the confidante said of Dr. Khan in an interview. "I don't think he is lying, but not perhaps telling the whole truth."
Iran has insisted that all of its centrifuges were built purely for peaceful purposes, and last week it signed an agreement to allow deeper inspections.
But for 18 years Iran hid the centrifuge operations from the agency's inspectors.
In Pakistan, the disclosure of the investigation is already complicating the political position of General Musharraf, who narrowly escaped an assassination attempt a week ago. An alliance of hard-line Islamic political parties has already assailed him for questioning the scientists, saying the inquiry shows he is a puppet of the United States.
Any attack on Dr. Khan, hailed as the creator of the first "Islamic bomb," is likely to be seized by the Islamist parties as a major political issue. Many Pakistanis opposed the American-led invasions of Afghanistan and Iraq, as well as what is seen as the United States' one-sided support of Israel. Many also perceive the United States as trying to dominate the Muslim world — and through pressure on the nuclear scientists, to contain its power.
While General Musharraf was responsible for sidelining Dr. Khan nearly three years ago, he has also praised him. When the nuclear and military establishments of Pakistan gathered for a formal dinner early in 2001 to honor Dr. Khan's retirement, General Musharraf described him this way, according to a transcript of his speech in a Pakistani archive: "Dr. Khan and his team toiled and sweated, day and night, against all odds and obstacles, against international sanctions and sting operations, to create, literally out of nothing, with their bare hands, the pride of Pakistan's nuclear capability."
European and American officials have a different view of Dr. Khan, from his work from 1972 to 1975 in the Netherlands at a centrifuge plant, Urenco.
At the plant, Dr. Khan gained access to centrifuge designs that were extremely sensitive, records from a later investigation show. Suddenly, around 1976, Dr. Khan quit and returned to Pakistan. Not long after, Western investigators say, Pakistan started an atom bomb program that eventually began to enrich uranium with centrifuges based on a stolen Dutch design.
Investigators in the Netherlands found a letter he wrote in the summer of 1976, after having returned to Pakistan, to Frits Veerman, a technician friend at the plant. "I ask you in great confidence to help us," Dr. Khan wrote, according to an article by David Albright, a nuclear expert, in The Bulletin of the Atomic Scientists. "This is absolutely urgent."
Dr. Khan asked for help on how to etch special grooves on a Dutch centrifuge's bottom bearing, a critical part. The grooves were to aid the flow of lubricants. He also asked if Mr. Veerman might like to vacation in Pakistan "and earn some money at the same time?"
Suspicious, Mr. Veerman gave the letter to officials at Urenco. It was eventually used against Dr. Khan when he was put on trial in absentia in the Netherlands. In 1983, he was sentenced to four years in prison for stealing nuclear secrets. The conviction was later overturned, however, on a legal technicality.
By 1986, American intelligence had concluded that Pakistan was making weapons-grade uranium. And Dr. Khan was making no secret of his expertise: he published two articles that advertised his knowledge. He did so, he wrote, "because most of the work is shrouded in the clouds of the so-called secrecy" controlled by Western nuclear powers.
At around the same time, Iran made its secret deal and obtained basic centrifuge designs, the ones that now bear Pakistan's technological signature.
But it was in the mid- to late 1990's, as American sanctions tightened, that Pakistan made its biggest deal — with North Korea, American intelligence officials have said. Though Pakistan continues to deny any role, the laboratories are believed to have been the centerpiece of a barter arrangement of nuclear technology for missiles. South Korean intelligence agents discovered the transactions in 2002 and passed the information to the C.I.A. In the summer of that year, American spy satellites recorded a Pakistani C-130 loading North Korean missile parts in North Korea.
Earlier this year the State Department barred American transactions with the Khan laboratory because of the missile deal.
Pakistani officials say that since Dr. Khan's retirement, he has no longer been officially affiliated with the laboratory that bears his name. Still, one former Pakistani military official described him as a proud nationalist who saw himself as a Robin Hood-like character outwitting rich nations and aiding poor ones. Dr. Khan, he said, "was not that sort that would think it was a bad thing" to share nuclear weapons technology. "In fact, he would think it was a good thing."
David Rohde reported from Pakistan and Boston. William J. Broad and David E. Sanger reported from Vienna, New York and Washington.
Copyright 2003 The New York Times Company