Burmese cyclone survivors face a massive crisis unless they are urgently delivered aid, leading aid agencies have warned – while Prime Minister Gordon Brown called on Burma’s generals to ease restrictions on outside assistance.

A likely death toll of 100,000 could rise to 1.5 million without provision of clean water and sanitation, Oxfam told the BBC and other news agencies today.

The International Rescue Committee said that without a massive delivery of aid, Burma faced “unimaginable tragedy”.

Eight days after Cyclone Nargis struck, the United Nations estimates only a quarter of survivors have received any aid so far.

The military government is still refusing to allow many foreign nationals into Burma to distribute relief.

The blocking of aid to the victims of Cyclone Nargis in Burma is “utterly unacceptable”, the Prime Minister said this weekend.

The ruling military junta is being urged by Gordon Brown and other world leaders to allow foreign aid workers into the country to help assist the relief effort, but have so far refused. Instead, the regime has indicated that the government would distribute the aid itself.

Speaking on his visit to the South West the PM said: “There are people suffering in Burma, there are children going without food, there are people without shelter.

“It is utterly unacceptable that, when international aid is offered, the regime will try to prevent that getting in.

“I’m determined to work with the rest of the international community to make sure that people in need of help, people who face a long and terrible time ahead because of the loss of their homes, and because there is famine, get all the help they need, and we will be working with the United Nations and other countries to make sure that that happens.”