BEIJING, Oct 18 (Reuters) - China has zero tolerance for corruption within the ruling Communist Party, President Xi Jinping said on Wednesday in a speech at the opening of a key party congress.

Having warned that rampant graft threatened the legitimacy of the party, Xi has overseen a sweeping crackdown on corruption that has felled numerous high-ranking officials within the party, government and military. (Reporting by Christian Shepherd and Stella Qiu; Writing by Michael Martina; Editing by Paul Tait)