British campaigners pushing for political change in Burma last night accused the country's oppressive regime of a "token" gesture in allowing a meeting between a United Nations envoy and opposition leader Aung San Suu Kyi.

Ibrahim Gambari held talks lasting about 90 minutes with the figurehead of the pro-democracy movement, who has been held under house arrest for the past 12 years.

It sparked hopes that Mr Gambari, who also wants to meet with the junta's top generals, might be able to secure a breakthrough in the crisis.

But Mark Farmoner, acting director of the Burma Campaign UK, said he was not optimistic that the regime, which has brutally clamped down on street protests, was about to change its tune.

He said: "It is a token gesture from the regime to allow them to meet. If they were genuine about reform then its troops would stop arresting and shooting people."

Earlier, hundreds of people took to Britain's streets in support of the Burmese people.

About 3,000 demonstrators marched past Downing Street in central London and called for the international community to step up pressure on the brutal dictators. There were also gatherings in Newcastle and Brighton, arranged through discussion groups on the internet.

In London, the march was led from Trafalgar Square by a Buddhist monk while various members of the UK's Burmese community, many of whom have fled persecution, carried banners, flags and large portraits of Suu Kyi.

John Jackson, a founding member of the Burma Campaign UK, who has been to the country to interview Suu Kyi three times, said he was very hopeful that continuing international pressure would make its mark.

He said that although there was no "silver bullet" for solving the crisis, it was important that every country play their roles in pushing for further effective sanctions on the junta.

"In Burma, the organisation, discipline and strength of the demonstrations have been the most remarkable thing," said Mr Jackson.

"That is what makes me think that this time it is not a movement that will simply just be put down by troops on the streets."

He added that there was evidence that possible cracks were beginning to appear in the military's organisation, with some troops refusing to fire on protestors.

He called on Prime Minister Gordon Brown to ensure that the EU presented a united front in the next few days.

But despite Mr Jackson's optimism, in Burma more troops have been drafted in to the largest cities and scores more protestors arrested.

It is estimated that as many as 1,000 protesters are now being held by the regime in over-crowded prisons, university buildings and other educational institutes.

Burmese state television has put the death toll from the violence at ten, but dissident groups estimate that at least 200 may have died.