Hundreds of supporters of Sri Lanka's ruling coalition led by a cabinet minister have rallied outside the British Embassy in the Sri Lankan capital, condemning what they say is London's support for minority Tamil separatists abroad.
The protesters, led by construction and housing minister Wimal Weerawansa, denounced the British government for allowing Tamil expatriates to hold a demonstration against Sri Lanka president Mahinda Rajapaksa, who visited London this week.
Mr Weerawansa said the British government has silently supported the "Tamil terrorists" by allowing Tamil Tigers to hold protests.
Last year, Sri Lankan government forces ended a 25-year civil war, beating Tamil Tiger rebels who were fighting for a separate homeland.
After the protest march in Colombo, Mr Weerawansa said: "We all have taken to the streets against this uncivilised act of the British Government."
He described the Tamil activists as terrorists and said they should not be allowed to demonstrate as the Tamil Tiger group is banned in Britain.
Mr Rajapaksa had been due to address the Oxford Union debating society this week, but the event was cancelled. The union said in a statement that "due to the sheer scale of the expected protests, we do not feel that the talk can reasonably and safely go ahead as planned".
The British High Commission said in a statement that the British Government had no involvement in the decision to cancel Mr Rajapaksa's address. A spokesman could not immediately be reached for comment on Mr Weerawansa's allegations.
Mr Rajapaksa has become an increasingly dominant figure in Sri Lanka. After the crushing military defeat of the rebels, he easily won re-election. His chief political rival and former army chief is now serving a jail sentence for 30 months, after being convicted by a military court. Critics say the case amounted to a political vendetta.
Mr Rajapaksa's government has resisted international calls for an independent examination of suspected rights abuses committed during the civil war, by both the Tamil Tigers and government forces.