A consignment of bales of plastic sheeting were sent on Monday night from a government store in Dubai - the first of four such flights as part of a £5 million UK aid package.

Supplies were trickling into the country on Monday amid renewed pressure on the ruling junta to lift its block on international help getting into the country. It has emerged that the Queen has made a "significant" personal donation to the relief effort.

Up to 5,000 square kilometres of Burma are still underwater following the devastating Cyclone Nargis more than a week ago. An estimated 100,000 people have already perished in the disaster, but aid agency Oxfam has warned this figure could multiply 15-fold, with further torrential rain expected.

On Monday Gordon Brown urged the Burmese authorities to give "unfettered access" to humanitarian agencies seeking to help survivors and pledged that Britain would use its chairmanship of the UN Security Council to press for action.

Mr Alexander and his EU counterparts are expected to agree a formal statement demanding that the Burmese regime allow full access to aid workers to distribute humanitarian assistance.

The crisis will be debated in the Commons on Wednesday after the Tories opted to devote part of an Opposition Day to it.

The Royal Navy ship HMS Westminster is heading for Burma to help humanitarian operations.

Conservative leader David Cameron called for aid should be dropped from the skies or brought in by sea if access does not improve dramatically within the next day, saying that any failure by Burma to allow aid in would constitute a "crime against humanity".

Foreign Secretary David Miliband said the "malign neglect" of the Burmese junta was turning a natural disaster into "a humanitarian catastrophe of genuinely epic proportions".