Tens of thousands of protesters marched yesterday against Prime Minister Tony Blair on the eve of a rally of his Labour Party where a struggle over the leadership looked set to steal the headlines. Activists shouting "Blair must go!" and chanting opposition to the Iraq war and to nuclear weapons streamed through the centre of the northern city of Manchester, which will host Labour's annual conference from today until Thursday. It will be Blair's final conference as party leader after nine years in office and three successive election victories.

Blair's backing for the US-led war on Iraq, his policies in the Middle East and his reforms of public services have angered many in Labour, leading to a slide in his popularity.

He was forced earlier this month to say he would resign within a year as rows over the succession exploded into public.

"The message we are trying to get across to the Labour Party is that it really is time for Blair to go," British Muslim Initiative spokeswoman Yasmin Ataullah, 32, said at the protest, organised by the "Stop the War" coalition.

Blair's sister-in-law, Lauren Booth, fronted one of the anti-war demonstrations, saying it was a "massive embarrassment" to be related to the prime minister and urging him to resign.

"This is a political question. This is not a personal vendetta," said Booth, who is the half-sister of Blair's wife Cherie, a human rights lawyer.

In reply to a question whether her role here would embarass the Blair family, Booth replied: "We are embarassed to have him as prime minister. He should be embarassed about what he's done, not the people here."

Booth, a journalist and commentator who has traveled to the Palestinian territories, accused her brother-in-law of being "a disaster" in the Middle East, adding that the situation in the region was on a "razor's edge."

"We're standing with our Muslim brothers and sisters," she said before adding: "Free Palestine."

She warned that the campaign against British foreign policy would continue if finance minister Gordon Brown, who is widely tipped to replace Blair when he steps down within the next year, fails to change course.

Police estimated the number of protesters at around 20,000 and said there had been no arrests by mid-afternoon. Organisers said tens of thousands more had taken to the streets.

Blair will face criticism of policy from delegates at the party conference, though the prospect of a resurgent opposition Conservative Party may prompt many to put on a united front, at least for the cameras.

Behind the scenes, though, there will be lively discussion of Blair's departure and successor, Labour parliamentarians said.

Brown has been waiting for years to succeed Blair but some in Labour fear the dour Scot lacks the charisma to win elections and they want an alternative.

Blair loyalist John Hutton called for a real contest between Brown and another heavyweight figure.

Brown ally Ed Balls, widely thought to be a future finance minister if Brown becomes leader, gave a flavour of a Brown premiership, saying he would be a tough negotiator in Europe. Brown could be as tough towards his EU counterparts as "Iron Lady" Margaret Thatcher was, an aide said.

PHOTO CAPTION

Demonstrators wave placards during an anti-war protest march, in Manchester, northern England, Saturday Sept. 23, 2006. (AP)