Gabon opposition leader challenges vote as mediation mission postponed

By Gerauds Wilfried Obangome LIBREVILLE (Reuters) - Gabon's opposition leader lodged a constitutional court challenge on Thursday against a presidential election he narrowly lost, hoping to overturn a result whose validity has been questioned at home and abroad. Former foreign minister Jean Ping lost the Aug. 27 election to President Ali Bongo by fewer than 6,000 votes, an outcome that sparked days of riots in which at least six people were killed. Ping's spokesman said in a statement he would s