LONDON - Facebook Inc said on Wednesday it had added labels to social media posts by both U.S. presidential candidates explaining that election vote counts were still ongoing.

"Once President Trump began making premature claims of victory, we started running notifications on Facebook and Instagram that votes are still being counted and a winner is not projected," Facebook said in a statement.

(Reporting by Jack Stubbs and Elizabeth Culliford; Editing by Alison Williams) ((jack.stubbs@thomsonreuters.com; Reuters Messaging: jack.stubbs.thomsonreuters.com@thomsonreuters.net))