Nearly 4,000 people are blocking roads around the Houses of Parliament after breaking through police lines.

Most are camped on Parliament Square as MPs return after the Easter break.

On Sunday, Gordon Brown sent a special envoy to the United Nations in New York for "urgent" talks on Sri Lanka, a former colony.

The protest for the UK to intervene Sri Lanka's civil war is now entering a third week.

Tamil UK head jailed for terrorism

Last Friday the Tamil Tiger's top man in the UK was convicted of two terrorism charges.

Arunachalam Chrishanthakumar, 52, from Norbury, was the leader of the Liberation Tigers of Tamil Eelam group in the UK - a banned organisation since 2000.

The jury found him guilty of separate bomb and of receiving documents for the purpose of terrorism.

Previous violent protests

There was chaos two weeks ago when an illegal pro Tamil erupted in violence. As demonstrators threw themselves into the Thames and shut Westminster Bridge and surrounding roads.

Officers, police boats and vans had ringed the area which is filled with chanting flag waving protesters, openly displaying the emblem of the Tamil Tigers - a banned terrorist group in the UK.

Half of the UKs 300,000 Tamils live in London.

UN call for "urgent ceasefire" - Civil war nearing end

The upheaval comes during the death throws of the Tamil Tiger uprising and a 25 year old civil war in Sri Lanka draws to an end.

The United Nations says 150,000 people are trapped in the northern war zone while Tamils claim they are victims of human rights abuses.

Sri Lanka's government has rejected calls for a ceasefire with the rebels, who want independence - the group is staring defeat in the face after being pushed back onto a narrow peninsular.

Foreign Secretary David Miliband said the UK government was "very concerned" about civilians caught up in fighting and stressed the need for a humanitarian ceasefire.

The United Nations says more than 2,800 civilians may have been killed and 7,000 others injured in the fighting in the north-east in the last two months. The Sri Lankan government disputes these figures.

Photo - Flickr -  Quarsan