GENEVA - Iran has pledged to open its recently revealed uranium enrichment plant to UN inspectors, possibly in the next few weeks, according to a senior EU envoy involved in the negotiations.

Officials from six world powers met with Iran in Switzerland on Thursday for nuclear talks. (Dominic Favre/Reuters) Javier Solana, who formally headed the negotiations Thursday in Switzerland, said Iran and the six world powers also agreed to a second round of talks regarding Tehran's contentious nuclear program.

Iranian officials met with permanent members of the UN Security Council and Germany in Genthod, northeast of Geneva, in an attempt to persuade Tehran to freeze its uranium enrichment program.

And in a surprise development, American and Iranian delegates reportedly met for their first known one-on-one meeting in years.

The U.S.-Iran meeting, the Iranian pledge to open the plant to inspectors and the round of talks are encouraging signs that the discussions might be more fruitful than originally believed. Western officials were discussing the imposition of new sanctions on Iran after learning last week of a second uranium enrichment facility under construction.

Concerns about Iran nuclear program

Iran insists the program is peaceful and for energy purposes. The West fears the program may be geared toward producing weapons and has demanded the doors be open to the UN nuclear inspectors.

Uranium processing is a key aspect of any nuclear power program as the mineral needs to be enriched to fuel a nuclear reactor producing electricity - or to be turned into bomb-making material.

Solana was upbeat before Western delegates, a three-man Iranian negotiating team and representatives from Russia and China began the one-day closed talks.

Iran was expected to bring a broad range of geopolitical issues to the table, while the six powers were seeking to soften Iran's resistance to freezing its uranium enrichment program.

Rare meeting between U.S., Iran

The U.S.-Iran meeting was also a positive sign for negotiators.

U.S. spokesman Robert Wood said U.S. Under Secretary of State William Burns met with Saeed Jalili, Tehran's chief negotiator during a lunch break at Thursday's seven-nation talks in Geneva.

Two other Western diplomats were also briefed on the discussion, Wood said.

Wood declined to elaborate on what was discussed during the high-level talk.

The sidebar meeting is the first known direct meeting between Washington and Tehran in about 30 years. Washington severed relations with Tehran in 1980 during a hostage crisis in the wake of Iran's Islamic Revolution.

There has been a spike in international pressure on Iran since the leaders of the United States, France and Britain announced last week they have disclosed intelligence information to the International Atomic Energy Agency that confirms an underground nuclear facility in Iran and have demanded an in-depth investigation.

The U.S. has signalled it is already contemplating new and tighter sanctions on Tehran, reflecting expectations that the talks may end in failure. But diplomats at UN headquarters in New York said there has been no discussion of a new sanctions resolution.

Previous sanctions

Several said they wanted to wait for a report from the UN nuclear agency on its planned inspection of Iran's newly disclosed nuclear facility and to see Tehran's response to the incentives if it starts negotiations.

The UN has imposed three previous sets of sanctions on Iran for pursuing its uranium enrichment program, which the Islamic country says is for civilian reactors but the international community worries could be used to make fuel for nuclear weapons.

The first sanctions in 2006 focused on banning trade in materials, equipment, goods and technology that could contribute to the nuclear program.

The sanctions were expanded in 2007 to include arms exports from Iran, and in 2008 Iran was restricted from importing technologies that could be used for both civilian and military purposes.

With files from The Associated Press