TRIPOLI - Libya has appointed ex-foreign minister Ali Abdussalam Treki as its envoy at the United Nations in New York, replacing the previous ambassador who renounced the Libyan leadership, a senior government source said."Dr Treki has been appointed as Libyan envoy to the U.N. to replace (Abdurrahman Mohamed) Shalgham," the source, who did not want to be identified, told Reuters.