VIENNA, Aug 30 (Reuters) - Partitioning the breakaway Serbian province of Kosovo is not an option for Serbia or Kosovo Albanians and is not on the agenda of a last-ditch bid for compromise between them, a European Union mediator said on Thursday. "The question of partition...has never been on the agenda of the troika or raised by either party," said EU diplomat Wolfgang Ischinger, after an initial round of separate talks between the two sides and a 'troika' of United States, Russian and EU envoys.