The biggest crowds in Europe were expected in Britain, Spain and Italy, whose governments backed US President George W. Bush's call to war to oust Saddam Hussein despite massive public opposition.

In London, two anti-war demonstrators climbed to the top of London's landmark Big Ben clock tower early Saturday, as opponents of the US-Anglo invasion of Iraq prepared to kick off a march from Hyde Park to Trafalgar Square at noon (1200 GMT) to demand an end to the occupation of the oil-country.

The Stop the War Coalition, which helped bring more than one million people into the streets on London in February 2003 to denounce the Iraq war, said tens of thousands of people were expected to join Saturday's march.

British news channel Sky showed pictures of two men, perched at the level of the clock more than 45 metres (150 feet) from the ground. They were roped together and appeared to have climbing equipment.

In Spain, thousands of people, with the horrors of last week's Madrid train bombings fresh in their minds, were expected to join anti-war marches.

The attacks by suspected Islamic extremists killed 202 people and led to the downfall of Spain's pro-US government in elections three days later and rocked the US-led coalition in Iraq.

Some 60 Spanish political groups have urged Spaniards to turn out en masse for Saturday's protest.

Protest rallies were also scheduled in Italy, where a majority of people favour pulling out Italian troops from Iraq at the end of June, as well as in France, Germany and the United States.

In France, an early opponent of the Iraq war along with Gremany, anti-war rallies were planned in several cities, including Paris, Marseille, Lyon and Toulouse.

In the United States, protest organisers said they hoped their ranks might be swelled in the aftermath of the Madrid train bombings.

In Australia, thousands of anti-war activists also staged rallies to mark the first anniversary of the US-led war. Speakers at the rallies called for Australian troops to be sent home from Iraq and attacked Prime Minister John Howard's conservative government's strong ties with the United States.

In Tokyo, organisers claimed 30,000 people had turned out to call for peace in Iraq and the immediate withdrawal of US and Japanese troops.

Hundreds of people also rallied in Muslim-majority Indian Kashmir and in Bangladesh to demand foreign troops withdrawal from Iraq.

In the Philippines, riot police Saturday used water cannons to disperse a group of about 100 demonstrators who tried to march on the US embassy in Manila to protest the Iraq war.