MOSCOW, Aug 4 (Reuters) - A Russian court on Wednesday rejected an appeal by Kremlin critic Alexei Navalny"s lawyers against a decision to label his Anti-Corruption Foundation an "extremist" group, his lawyers said, a move that outlaws it and other organisations. "The decision has been left in place without any changes," a representative of lawyer Ivan Pavlov wrote on Telegram. Navalny, who is serving a 2-1/2-year jail sentence on charges he says are trumped up, has denied extremism allegations. He has casting them as an attempt to stamp out opposition to the ruling United Russia party ahead of the parliamentary vote in September.