Tamils have been staging protests in London over the last two weeks
Tamils staging an ongoing protest in central London have blocked roads around Parliament Square as they demand a ceasefire in Sri Lanka.
The Metropolitan Police said about 3,500 people had gathered at Parliament as MPs returned after Easter.
The demonstrators began rallying two weeks ago over the conflict between the Sri Lankan government and the Tamil Tigers separatist group.
Protesters want the UK to end the war in Sri Lanka - a former British colony.
The numbers at the protest swelled from hundreds to thousands overnight on Sunday after news broke that at least 25,000 civilians had fled fighting in a Tamil Tiger-held area in the north of the country.
Suren Surendiran, of the British Tamils Forum, said those at the demonstration "did not want words any more" and he called on the UK government to take the issue to the UN Security Council in order to implement a ceasefire.
The prime minister is deeply concerned by the current conflict and there should be an immediate ceasefire
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.