The United Nations' humanitarian chief John Holmes is being sent to Burma to try to persuade the government to allow the free flow of international aid for the cyclone victims.

The UN secretary general, Ban Ki-moon, made the decision after an emergency meeting with diplomats at the organisation's New York headquarters.

Earlier, Thailand's prime minister, Samak Sundaravej, spent half a day in the Burmese capital trying to negotiate with the military government for more access visas.

But the effort to mediate failed with the Thai leader returning to Bangkok empty-handed.

Mr Samak says the Burmese government insists that the cyclone survivors were already being well cared for.

But our correspondent in Bangkok, Peter Lloyd, says that account is sharply at odds with independent reports from the cyclone-affected Irrawaddy delta and aid agencies.

The UN has increased its estimate of those severely affected by Burma's cyclone to 2.5 million - a million more than previously thought to be in need.

The Red Cross is estimating that there could be as many as 128,000 dead.

In revised figures, the Burmese government says just 62,000 people are dead or missing and 600,000 survivors are being cared for in 600 makeshift camps.

The UN has warned that many more may die unless food, water and medicine supplies reach a further two million people in urgent need of help.

British PM refuses to rule-out direct intervention
The British prime minister has backed calls for an emergency summit on Burma's cyclone disaster.

Gordon Brown also refused to rule out direct intervention.

He told the House of Commons that the relief efforts by Burma's ruling junta were not good enough.

"That a natural disaster in Burma by the actions of a despicable regime has been turned into a human catastrophe - a man made catastrophe - as the result of their actions," he said.

Mr Brown wants the UN chief to travel to Burma as soon as possible.

Military searching for foreign reporters
Burma's military government tightened access to the cyclone disaster zone on Wednesday, insisting they can care for survivors without the help of foreign disaster experts.

Reports say the regime has imposed a ban on all foreigners from visiting the Irrawaddy delta and begun searching buses and cars for reporters trying to reach the cyclone affected area.

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