The Roehampton Vale sports ground was awash with colour as more than 20,000 Tamils from all over the capital gathered for the Pongku Thamizh rally.

The rally was organised to urge the Sri Lankan government to recognise the Tamil people's call for self-determination and a separate state, Tamil Eelam.

The July 12 event began with the lighting of the common flame of sacrifice followed by a moment of silence before local groups performed traditional music, poetry and dancing.

A spokesman for the British Tamil Forum said: “It was a fantastic event with the turnout far exceeding our expectations. The overwhelming response of British Tamils was impelled by the continued sufferings in Sri Lanka and the Tamils anger over the attitude of the international community.”

Speakers involved in struggles in Belfast, Kosovo and South Africa also gave rousing speeches to the packed crowds comparing the plight of the Tamils to their own back in the 1980s and 1990s.

Virendra Sharma, Southall MP, said: “There is no quick fix. Sri Lanka is not just a failed state, there is so much more. I understood that the crowd felt Tamil Eelam was the only solution and promised to work with the British government to force the Sri Lankan government to take steps towards solving the conflict.”

Independent sources said that more than 25,000 people attended the event though the estimation by the Metropolitan Police was between 20,000 and 30,000.

Baroness Sarah Ludford, MEP for London, said: “It is deeply important to anyone concerned with human rights and justice that we get a political solution that recognises the cultural and linguistic identity of the Tamils. I urge all parties to return to the negotiating table and called for an end to human rights abuses.”

Messages of support were also received from Tony Benn MP, Stephen Hammond MP, Simon Hughes MP and Susan Kramer MP.