Four aid flights are due to land in Burma as up to two million people struggle to survive in the aftermath of Cyclone Nargis.As relief agencies warned that aid deliveries have been minimal, a US military aid flight left Thailand earlier carrying water purification systems and supplies to ward off water-borne diseases.Medecins Sans Frontieres said three cargo planes from Europe carrying medical material and other supplies are scheduled to arrive in the stricken country later.In a statement MSF said: "More than one week after the disaster, despite the sending of three cargo planes and some positive signals, it has been very difficult to provide highly needed supplies for the heavily affected population in Myanmar."In the areas where we have been, we haven't seen any aid being delivered so far, so the amount that has reached people in the areas where we are had been minimal."MSF had a large presence in Burma before the cyclone. Aid agencies that did not, are having even greater difficulties.But while the country's reclusive military government has begun accepting aid from the outside world, including the United Nations, it will not let in foreign logistics teams, who are ready and waiting for Burma visas in the Thai capital, Bangkok.The European Commission has called for an urgent meeting of European Union ministers in charge of humanitarian aid to beef up the EU response to the emergency, the Commission has said.Louis Michel, commissioner for development and humanitarian aid, intends to travel to the cyclone-hit Asian country immediately after the meeting.On Sunday, the UN humanitarian agency said between 1.2 million and 1.9 million were struggling to survive in the aftermath of the storm that struck nine days ago.Most of the victims were killed by the 12-foot (3.5 metre) wall of sea-water that hit the delta along with the Category 4 cyclone's 120 mph winds."Given the gravity of the situation, including the lack of food and water, some partners have reported fears for security, and violent behaviour in the most severely afflicted areas," the United Nations Office for Coordination of Humanitarian Affairs said."The number of deaths could range from 63,290 to 101,682, and 220,000 people are reported to be missing."It said "acute environmental issues" pose a threat to life and health."Unless there is a massive and fast infusion of aid, experts and supplies into the hardest-hit areas, there's going to be a tragedy on an unimaginable scale," said Greg Beck of the International Rescue Committee.In the delta town of Labutta, where 80 per cent of homes were destroyed, authorities are providing one cup of rice per family per day, a European Commission aid official said.In a blow to the stumbling relief effort a boat carrying some of the first aid to survivors sank, the International Federation of Red Cross and Red Crescent Societies said.The boat was believed to have hit a submerged tree in the Irrawaddy delta. The accident highlighted the enormous logistical difficulties of delivering aid, with roads washed away and much of the delta turned to swamp.Burma's own figures put the death toll on Sunday to 28,458 dead and 33,416 missing from the storm on the night of May 2 and early on May 3.