China has expressed “serious concern” to Sudan’s government about the expulsion of aid workers from Darfur, yet won’t back United Nations Security Council pressure to reverse the decision, China’s envoy said. “We have openly expressed our concern,” China’s ambassador to the UN, Zhang Yesui, said in an interview in New York. “We have advised the Sudanese government to be restrained. We told them we do not want the humanitarian situation to worsen.”