 UN Secretary-General Ban Ki-moon called on Central Asian states to work together to tackle the disastrous effects of the shrinking Aral Sea on Sunday after local people urged the United Nations to resolve a regional dispute. Much of the former bed of what was once the world's fourth largest lake is now a desert covered with scrub and salt flats. It shrank by 70 percent after Soviet planners in the 1960s siphoned off water for cotton irrigation projects in Uzbekistan. "I was so shocked," Ban said after viewing the damage by helicopter, describing it as "clearly one of the worst environmental disasters in the world". He was on a tour of the five former Soviet republics of Central Asia that lie on some of the world's biggest untapped oil, gas, uranium and gold reserves. The people living around the Aral Sea are some of the poorest in the region and struggle with declining fresh water supplies and fish stocks, pollution and violent sand storms. In 1990 the sea split into a large southern Uzbek part and a smaller Kazakh portion. "I urge all the leaders (of Central Asia), including President (Islam ) Karimov of Uzbekistan to sit down together and try to find solutions," said Ban, hours before a scheduled meeting with the Uzbek leader. "All specialised agencies of the United Nations will provide necessary assistance and expertise," he said. The United Nations has billed Ban's week-long trip, also taking in Turkmenistan, Kyrgyzstan, Tajikistan and Kazakhstan, as a chance to discuss regional cooperation, nuclear non-proliferation, climate change and development. Once isolated from the outside world, the region has gained global significance because of its proximity to Afghanistan. In Moynak, once on the coastline of the Aral Sea but now surrounded by sand, Ban was met by a group of about 20 townspeople who complained about the possible impact of the Rogun hydroelectric power plant that Tajikistan wants to build. Tajikistan hopes the new Rogun plant will solve the country's chronic lack of energy by nearly doubling domestic electricity output. Uzbekistan is concerned about the environmental and economic fallout of Rogun and other developments affecting the Aral Sea. "If Rogun is constructed we will be in a much more difficult situation," local teacher Zhanabay Zhusipov told Ban. "There should be an international inquiry by the United Nations on all these hydro-electric power stations." He and other local townspeople recalled playing in the sea as children and said that since the coastline had receded, local people's health had deteriorated. Uzbek officials told Ban that wind blows up dust carrying toxic chemicals from the dried-out seabed. Uzbekistan wants the UN to get involved in tackling the effects of the Aral Sea shrinking, but a UN official said privately that Uzbekistan was putting too much emphasis on international aid and not enough on regional cooperation.