The new UN humanitarian chief warned Sunday that humanitarian efforts in Darfur could collapse if the situation deteriorates and aid workers are prevented from doing their work. John Holmes spoke while visiting a refugee camp on the outskirts of the town of El-Fasher in Darfur, on his first tour of the troubled region since becoming the UN's top humanitarian official. Some 45,000 people have taken refuge in the camp from the region's spiraling violence. "This humanitarian effort is fragile," he said. "If the situation deteriorates, it could collapse. The risk is high, it is not imminent, but if things deteriorate, people may not want to maintain their efforts."