MADRID, March 20: Hundreds of thousands took to streets across the world on Saturday to demand the withdrawal of US-led occupying forces from Iraq on the first anniversary of the start of the invasion.

Journalists estimated at least a million people streamed through Rome in probably the biggest single protest, and in London two anti-war protesters evaded tight security around parliament to climb the landmark Big Ben clock tower.

From Tokyo to San Francisco, demonstrators accused US President George Bush of having made the world a more unsafe place by invading Iraq and triggering a violent backlash from militant groups.

But there were fewer demonstrators than in the mass marches staged around the world in the run-up to the invasion.

In Iraq itself, many people said their lives had improved since Saddam Hussein was toppled, but others said a year of guerilla attacks and widespread lawlessness had left them fearful. No major attacks or protests took place.

"Your war, our dead" said one Rome protest banner directed at Italian Prime Minister Silvio Berlusconi, President Bush and British Prime Minister Tony Blair.

"This is a gigantic demonstration," Nobel prize-winning playwright Dario Fo said as a sea of rainbow-coloured peace flags bobbed above protesters marching to a rally at the Circus Maximus, site of an ancient Roman stadium.

Supporters of Mr Berlusconi, a staunch backer of the invasion who has also sent troops to Iraq, issued a statement criticizing the protesters and accusing them of having "paralysed" the capital.

"These aren't pacifist demonstrations. They are demonstrations against the United States, against the Italian government and, in many ways, against the West," Deputy Prime Minister Gianfranco Fini told the AGI news agency.

The protests began in Asia, where rallies took place in Australia, Japan, South Korea, Pakistan, India, Bangladesh and Thailand. They then moved to Europe through the day and more were expected in the Americas later.

In Spain, many protesters blamed the previous conservative government's decision to support the invasion for the March 11 Madrid train bombings that killed more than 200 people.

"The government took the country to war, but it was ordinary people who got hurt and killed by the terrorists," film producer Lila Pla Alemany said on her way to a protest in Barcelona.

Incoming Spanish Prime Minister Jose Luis Rodriguez Zapatero has pledged to pull Spanish troops out of Iraq.

'WANTED' POSTERS: In London, thousands streamed through central London carrying "Wanted" posters bearing the faces of George Bush and Tony Blair.