YANGON (AFP) - Aid groups said Sunday that supplies trickling into cyclone-hit Myanmar fell short of the enormous need, as the faltering relief effort suffered a new blow with the sinking of a Red Cross boat. The boat, carrying vital supplies of drinking water, rice, water and purification tablets, hit a submerged tree trunk as it travelled by river through the disaster zone. Much of the aid was lost, but no one was injured. "Apart from the delay in getting aid to people we may now have to re-evaluate how we transport that aid," said Michael Annear, disaster manager in Yangon for the International Federation of Red Cross and Red Crescent Societies. The death toll from Myanmar's devastating Cyclone Nargis has risen to 28,458, with 33,416 people still missing, state television announced Sunday. The pace of aid deliveries picked up Sunday, but as thousands of starving cyclone survivors turned out on the roads to beg for food and water, experts said far more was needed. Myanmar's ruling generals, who have refused to allow foreigners in to direct the relief effort, were also condemned for holding a national referendum at the weekend despite the devastation in the country's south. An AFP journalist who travelled from Myanmar's main city Yangon to the southern delta, which was ground zero in the disaster, reported there were at least 10,000 people lining the sides of the road, waiting for help. Hungry and thirsty, their numbers are building fast - and the only help arriving was from religious groups and well-wishers who pulled up to unload packets of rice and noodles. "Some opening-up on the part of the authorities is allowing us to get these materials to their destination," said Stephan Goetghebuer, director of operations of medical charity Medecins Sans Frontieres (MSF). "But it's no more than a drip-feed, really, given a serious response is more than required. We still need more back-up aid and personnel ready to leave." A cargo plane chartered by the International Committee of the Red Cross carrying 35 tonnes of aid was one of the latest to arrive. The ICRC said medical supplies on board could treat 250 trauma patients and provide three months of basic health care for 10,000 people. A mobile water treatment plant would be able to provide drinking water for 10,000 people. A Greek air force plane carrying aid landed Sunday in Yangon and its cargo was quickly unloaded, the Greek Foreign Ministry said. A second C-130 loaded with 23,000 tents donated by the Greek army, plus two tonnes of medicine and three tonnes of other provisions, left Athens on Saturday and is due to land in Yangon on Tuesday (tomorrow). The military government's refusal to open its doors has infuriated aid groups and foreign governments who say that unless they have free access, the toll from the disaster will rise dramatically as hunger and disease set in. "It's not true that nothing is happening at all, but not enough is happening," said Frank Smithuis, Myanmar country manager for MSF. French charity Medecins du Monde also said Sunday that Myanmar authorities had agreed to let it distribute its aid, which was arriving Monday (today). The international community has spoken out in increasingly concerned tones over Yangon's apparent sluggishness or suspicion when it comes to taking up offers of overseas and even non-governmental aid. British Foreign Secretary David Miliband accused Myanmar's ruling generals of "malign neglect", warning the aftermath of its cyclone was a "catastrophe of genuinely epic proportions." Sarah Ireland, East Asia director for development charity Oxfam, warned that all the factors were in place for a public health crisis that could multiply diplomats' estimates of 100,000 dead by up to 15 times. "It's perfect storm of factors such as a lack of water, sanitation, predicted heavy rain over the next week, lack of food as well as outbreaks of disease," she told a press conference.