Anti-war demonstrators scaled London's landmark Big Ben clock tower in a spectacular protest, as opponents of the US and British invasion of Iraq prepared to mark its first anniversary with a rally.
"Officers are at the scene trying to bring the protest to a peaceful solution," a spokesman for Scotland Yard said.
Police said they did not believe there was reason to fear a terrorist incident.
The scene at St Stephen's Tower, known as Big Ben, at London's House of Commons Saturday March 20, 2004, where two Greenpeace antiwar demonstrators scaled the tower. A large antiwar march in London was scheduled for later in the day. (Photo/ Michael Stephens/PA)
"We don't think it is terrorist related. We think they are anti-war," the spokesman added.
British news channel Sky News showed pictures of two men, perched at the level of the clock more than 45 meters (150 feet) from the ground. They were roped together and appeared to have climbing equipment.
The spectacular protest is an embarrassment for British security services who have been on near high alert following the Madrid train bombings on March 11 which killed more than 200 people.
Opponents of the US and British invasion of Iraq were later to mark its first anniversary Saturday with a major street march in London demanding an end to the country's occupation.
Tens of thousands were expected to join the main demonstration in London, starting at noon (1200 GMT) in Hyde Park and snaking its way to Trafalgar Square for an afternoon rally, the Stop the War Coalition said.
Buses were being laid on from more than 75 cities to bring protestors to the British capital.
Several thousand black balloons were to be released at 3 pm in memory of both Iraqi war victims and the 202 people killed in last week's train bombings in Madrid.
It will be a far smaller event than the million-strong march in February last year that underscored the scale of opposition within Britain to Prime Minister Tony Blair's decision to join the US thrust to oust Saddam Hussein.
But organizers were determined to make their voice heard.
"We want to call for an end of the occupation in Iraq," Lindsey German of the Stop the War Coalition told a news conference earlier in the week.
"Everything we said about the war has turned out to be true, and everything the (British) government said has turned out to be a lie."
Blair, to a greater extent than US President George W. Bush, argued that military action was essential in order to deal with Saddam's feared pursuit of chemical, biological and nuclear weapons.
No such weapons have been found, however, prompting the demonstration's keynote slogan: "No more lies, Mr. Blair."
Blair received a roasting Saturday from his newspaper critics over the war in Iraq, while papers which supported Blair's decision to commit British troops to the campaign to remove Saddam Hussein were notably quieter.
Most trenchant was the Independent, which used its entire front page to run a hard-hitting editorial piece condemning the initiative, titled: "A year of war that made the world a more dangerous place."
An opinion poll by Sky News television, released earlier this week, indicated that Britons are as divided as ever over the war, with 48 percent saying it was right, and 41 percent saying it was wrong.
The last big anti-war protest in London, also spearheaded by Stop the War, was last November when 100,000 to 200,000 converged on Trafalgar Square as Bush paid a state visit.
© 2004 AFP