Thousands of protesters were on the streets of Manchester

Demonstrators were protesting against government policies in the Middle East and nuclear weapons, on the eve of the Labour Party conference in the city.

The theme was "Time To Go" - a call to get troops out of Iraq and Afghanistan.

Police estimated 20,000 people took part. Stop The War Coalition had said it expected about 100,000.

One of the organisers, Yasmin Ataullah of the British Muslim Initiative, told the BBC they put the figures of demonstrators at 40,000 or higher.

"This is one of the biggest mobilisations outside London and I think there are tens of thousands here - 40 or 50,000 at least," she said.

The march began in Albert Square outside the city's town hall, before heading down Lower Mosley Street, Deansgate, Market Street, Cross Street and back to Albert Square for a rally.

A "ring of steel" was in place around the conference centres

Some protesters lay down in the road as part of a "die-in" to symbolise the number of casualties in Iraq.

Andrew Murray, chairman of the Stop The War Coalition, which helped organise the event, said: "The tens of thousands of people marching through Manchester represent the opinion of the majority of people in this country."

They held up banners which read "time to go" and "bring troops home".

A peace camp was set up at the nearby Peace Gardens earlier this week by families of serving troops.

Security cordon

There were also speeches against replacing the Trident nuclear weapons system.

The march is the 15th national demonstration organised by the Stop The War Coalition, CND and the Muslim Association of Britain, and is said to be the biggest of its kind ever held in Manchester.

Speakers included veteran peace activist Tony Benn, union leaders Tony Woodley of the T&G, and Keith Sonnet of Unison, Rose Gentle of Military Families Against the War, and Craig Murray, the former UK ambassador to Uzbekistan.

About 1,250 police were on duty during the march and rally.

Supt John O'Hare, public order commander at Greater Manchester Police, said: "We estimate that up to 20,000 protestors came to Manchester to take part in the 'Stop the War' march.

"On behalf of GMP I would like to extend my thanks to the organisers and those who took part in today's protest, for co-operating with us and behaving peacefully and lawfully."