BRUSSELS, April 4 (Reuter) - The leaders of the world's four biggest humanitarian organisations on Friday launched an unprecedented joint appeal for help for thousands of refugees trapped by fighting in easter Zaire. Sadako Ogata, the United Nations High Commissioner for Refugees, Carol Bellamy, executive director of UNICEF, Catherine Bertini, executive director of the World Food Programme and Emma Bonino, European Union Commissioner responsible for humanitarian affairs, said urgent help was needed in Zaire. "We appeal to the participants ... to fully consider the urgent humanitarian needs of hundreds of thousands of refugees and displaced Zaireans stranded in the war zone," they said in a statement. The appeal was timed to coincide with talks in South Africa between Zairean government officials and members of the rebel Alliance of Democratic Forces for the Liberation of Congo-Zaire. The rebels have captured a huge swathe of eastern Zaire from government forces since October last year, scattering thousands o

f Rwandan refugees and Zairean peasant farmers who lived in the area. Zaire has been plunged further into crisis by the prolonged absences of ailing President Mobutu Sese Seko, who has seen his 31-year grip on the central African country loosened by frequent visits to Europe for treatment for prostate cancer. Mobutu appointed opposition leader Etienne Tshisekedi as prime minister earlier this week, but the offer of six key government posts for the rebels was rejected by their leader Laurent Kabila. Tshisekedi, who failed to name a single Mobutu supporter in his 26-strong cabinet, was coming under increasing pressure in Kinshasa on Friday from politicians who say his action was unconstitutional. The statement from the four aid organisations said relief workers urgently needed access to areas from where reports of thousands of starving refugees were emerging. "We have witnessed the plight of the refugees ourselves," it said. "These people fled into the rain forest to escape the fighting and violence in the reg

ion. We are now trying to help them and prepare them for repatriation." "However, many thousands of Rwandan and Burundi refugees as well as internally displaced Zaireans remain out of reach. We are appealing to the international community for urgent assistance."