Several thousand demonstrators marched through central London Saturday calling for an end to the US-led war in Iraq and for the return of British troops from the country.

Protest rallies were also planned in Rome, Paris, Madrid, Copenhagen, Oslo and Helsinki, to coincide with a similar march in Washington.

The Stop The War coalition, which organized the London rally jointly with the Campaign for Nuclear Disarmament and the Muslim Association of Britain, said it expected at least 100,000 people to take part.

"Today coincides with the demonstration in Washington DC and is also the eve of the Labour Party annual conference," which Prime Minister Tony Blair will attend in the southern city of Brighton, Stop the War spokesman Viven Lehal told AFP.

The demonstrators were to set off from the Houses of Parliament around noon (1100 GMT), arriving at Hyde Park two hours later where the rally was to continue. British anti-war campaigners have been calling relentlessly for the return of the 8,500 British troops deployed as part of the US-led forces in Iraq.

"We want to withdraw the troops from Iraq. Clearly what happened in Basra this week shows that British troops aren't helping there, they make the situation worse," Lehal told AFP.

Renewed violence in Iraq

The past week saw an upsurge of tensions around the southern Iraqi city of Basra, where many of Britain's troops in the country are based.

British troops stormed an Iraqi police station after two British undercover soldiers were arrested by the police and then kidnapped by a Shiite militia. Authorities in Basra have been refusing to engage with British troops following the incident.

Saturday's protest was also called in protest at counter-terrorism measures proposed by the government in the wake of the London bombings in July, and perceived by critics as a threat to civil liberties -- and to mark concern at a sharp rise in racist incidents in the wake of the bombings, Lehal said.

The last such demonstration took place on March 19 when organizers claimed 110,000 people took to the streets although police estimated the figure to be closer to 45,000.

"I think even more people will be out today because of the attacks on London, on Muslims and events in Basra," said Lehal.

"The attacks prove a point we've long been making: the invasion and illegal occupation of Iraq have made us a major terrorist target. The only people who can't see that are in our government."

Activist Bianca Jagger, musician Brian Eno, Labour member of Parliament Tony Benn and the parents of British soldiers killed in Iraq were all due to address marchers.

Protests in Washington too

One soldier's mother, Sue Smith, was set to take a letter to Blair's office at Downing Street urging the withdrawal of troops from Iraq.

Another, Rose Gentle from Scotland, flew to Washington where she will march side by side with Cindy Sheehan, a killed American soldier's mother who has come to symbolize the US's anti-war movement.

The demonstrators are buoyed by opinion polls that show a growing majority disapprove of Bush's handling of the war and question the rationale for US military action.

"It seems to be playing out the way it did with Vietnam. As time goes on, more and more people begin to have doubts," said Frank Nicosia, a history professor who traveled by bus with his wife from Vermont to attend the march.

"Few people judge whether it's right or wrong, smart or stupid. They only ask does it effect me or doesn't it? That's beginning to happen now."

Anger in Paris

In Paris, about 60 protesters rallied near the US embassy on the central Place de la Concorde square.

The rally had been called by French, Franco-Iraqi and US groups including Americans against War, the French group Act against the War (ACG), the Association of Iraqis in France, an anti-racism group as well as a communist organization.

Banners read in French and Arabic: "Troops out of Iraq, Justice in Palestine", as well as "Incompetent Bush, why don't you take care of your hurricanes" and "Wanted, George W. Bush, war criminal."

Another rally was scheduled in the French capital for later Saturday.