Rebels advanced toward Congo's eastern provincial capital of 600,000 people Tuesday, sending tens of thousands of terrified civilians into a makeshift shelter as Congolese troops and UN tanks retreated. The sudden influx of an estimated 30,000 people tripled the size of the camp in Kibati in a matter of hours, said Ron Redmond, spokesman for the UN refugee agency. “It's chaos up there,” Redmond told The Associated Press from Geneva, citing UN staff in Congo. “These crowds of people coming down from the north have already started turning up there.” A hundred refugees a day, mostly women and children, also were fleeing across the border into Uganda, that country's Red Cross said. In Kibati, a few miles from the front line, young men lobbed rocks Tuesday at three UN tanks also heading away from the battlefield. The UN has 17,000 peacekeepers in Congo – the biggest mission in the world. “What are they doing? They are supposed to protect us,” said Jean-Paul Maombi, a 31-year-old nurse from Kibumba. The chaos in eastern Congo has been fueled by festering hatreds left over from the Rwandan genocide and the country's unrelenting civil wars. Renegade Gen. Laurent Nkunda has threatened to take Goma despite calls from the UN Security Council for him to respect a ceasefire brokered by the UN in January. Nkunda charges that the Congolese government has not protected his minority Tutsi tribe from a Rwandan Hutu militia that escaped to Congo after helping perpetrate the 1994 Rwandan genocide. Half a million Tutsis were slaughtered. Nkunda's ambitions have expanded since he launched a fresh onslaught on Aug. 28 – he now declares he will “liberate” all of Congo, a country the size of Western Europe with vast reserves of diamonds, gold and other resources. Congo's vast mineral wealth helped fuel back-to-back wars from 1997 to 2003. The UN says more than 200,000 people have been forced from their homes in the last two months, joining 1.2 million displaced in previous conflicts in the east. Outbreaks of cholera and diarrhea have killed dozens in camps, compounding the misery. On Monday, peacekeepers in attack helicopters fired at the rebels trying to stop them taking Kibumba, a village on the main road 50 km north of Goma. But fleeing civilians say the fighters overran Kibumba anyway. The rebels retaliated by firing a missile at one UN combat helicopter Monday, but missed, UN spokeswoman Sylvie van den Wildenberg said. Several foreign aid workers have fled fighting from Rutshuru as rebels closed in on the town, 70 km north of Goma, she said. The UN was trying to evacuate the workers from Rutshuru, where the rebels are fighting on the second of four fronts. Doctors Without Borders said essential medical staff who were not evacuated from Rutshuru Hospital said they could hear heavy artillery combat close by Tuesday. They said they had treated 70 war wounded since Sunday but most patients had fled the hospital. UN efforts to halt Nkunda's rebellion are complicated by the country's rugged terrain, dense tropical forests that roll over hills and mountains with few roads. On Tuesday, a UN official who spoke on condition of anonymity because of the sensitivity of the subject, said rebels in civilian clothes made several attempts to infiltrate Goma, but UN peacekeepers spotted them and forced them to return.