The top U.N. diplomat for humanitarian affairs toured a hospital and a refugee camp Sunday in northeastern Congo, where aid groups say 900 civilians have been slaughtered since Christmas by marauding Ugandan rebels, according to AP. After visiting camps for displaced people around the provincial capital of Goma, U.N. humanitarian chief John Holmes flew to the northern town of Bunia, said Sylvie van den Wildenberg, a spokeswoman for the U.N. peacekeepingmission in Congo. Holmes' trip comes amid an outcry from aid workers, who accuse U.N. peacekeepers of failing to protect civilians in the region. Some 100 aid and human rights organizations are calling on Holmes to insist that peacekeepers use force to protect ordinary people. Rebels from Uganda's Lord's Resistance Army have massacred around 900 people over the last month in an area north of Bunia, near the border with Sudan. The bloodshed was sparked after Ugandan troops backed by soldiers from Congo and Sudan began a joint operation in mid-December to crush the rebels. Some 17,000 peacekeepers are in Congo but they have been unable to stop the violence in this vast central African nation. Holmes began his four-day trip on Saturday in the capital, Kinshasa, then headed east to the Rwandan border and visited a refugee camp in Kibati still housing thousands displaced by fierce fighting last year. Holmes had planned to visit a remote hospital in Masisi, west of Goma, on Sunday, but the helicopter trip was called off because of bad weather, Van den Wildenberg said. Holmes instead toured a hospital in Goma, as well as a camp for Rwandan civilians who want to be repatriated.