Tsunami survivors and aid workers in the Solomon Islands complained Thursday that relief efforts were chaotic and slow as the disaster's scale became more clear, and the UN warned that thousands faced the threat of dangerous diseases. Reports of diarrhea were becoming more widespread, and officials were worried about possible malaria and cholera outbreaks because of unsanitary conditions in makeshift high-ground camps where thousands fled Monday's magnitude-8.1 earthquake and tsunami and were refusing to come down. The United Nations put the death toll from Monday's disaster in western Solomon Islands - higher than the Solomons' official tally of 28, though government officials say they expect more deaths to be confirmed. The UN said it estimated 50,000 people were affected by the disaster - 30,000 of them children who were "highly vulnerable" to diseases including malaria, which is endemic in the region. The government says 5,600 were left homeless. There has been no official tally of the missing. Government officials conceded the aid effort was going more slowly than they wanted, but blamed the remoteness of the affected region and a shortage of supplies in the capital, Honiara, that could be shipped to the disaster zone. Survivors picking through the rubble of shattered villages looking for food and supplies found more bodies on Thursday, and grew increasingly frustrated that they were being left to fend for themselves, including burying their neighbors who were killed. Military transport planes from New Zealand and Australia have flown in loaded with aid packages of tarps, water and food rations, and a police patrol boat has brought a shipment from Honiara. "We are under-resourced, we need bigger vehicles," said disaster official Jonathan Taisia at the main Red Cross center in hard-hit Gizo town, as a chartered helicopter landed with the latest load of tarps and food. Gizo's airport reopened Thursday, but Taisia said much of the aid coming into Gizo wasn't being distributed beyond depots because of vehicle shortages, and a lack of workers to load trucks or clear debris that had severed road links to outlying villages. Drinking water is in extremely short supply in Gizo, as is food and medicine. Most aid was being delivered to Munda, on a nearby island, and a shortage of boats hampered efforts. Most of the local fleet of canoes and other vessels was destroyed by tsunami waves up to 5 meters high that crashed ashore within minutes of the offshore quake Monday morning. "We have a problem with water, and sanitation is a big issue that needs to be addressed urgently," said Allen Alepio, one of a team of six doctors and 15 nurses who rushed to Gizo on Wednesday after the hospital was washed out. "We have reports coming in that there are diarrhea outbreaks in the surrounding areas," he said at a hilltop clinic. "The children especially are getting diarrhea." Nearby, nurse Hugo Losena bandaged bone fractures, stitched cuts and struggled to treat internal bleeding - the most common injuries among the three dozen people at the camp - but said he was running out of supplies. "The recovery operation is not going as fast as expected because of delays here in Honiara," Alfred Maesulia, an official in the Prime Minister's Department, told The Associated Press. "Suppliers don't have the volumes of relief materials we need to send." Alex Lokopio, the premier of Western Province, said the full impact of the disaster could be much worse than estimated so far, and that up to 40,000 people in his district of about 90,000 could be homeless. "Most of these people live along the coast. The tsunami washed all their houses away," he told The Associated Press. At Titiana, a village just 10 kilometers from Gizo but unreachable by vehicle because of chunks washed out of the road, residents buried two young boys they had found in the rubble of shattered houses, using a salvaged trunk for one coffin and making another from scrap wood. Rev. Tikeri Birlata, a Uniting Church minister in the village, said nobody knew where the boys' parents were, but that he would note the location of the graves in case they came back. Villagers were worried about the smell and possible disease caused by the bloated bodies. He was angry no help had yet reached the village. Survivors terrified by the more than 50 jolts that have struck the region since Monday's quake - including several registering magnitude 6 or stronger - say they are too afraid of another tsunami to come down from the hills.