BEIJING, July 16 (Reuters) - A U.S. Navy destroyer sailed near the disputed Spratly Islands on Saturday, the U.S. Navy said, its second such "freedom of navigation" operation in a week in the South China Sea.

On Wednesday, China's military said it had "driven away" the same ship, the USS Benfold, when it sailed near the disputed Paracel Islands.

The United States regularly carries out what it calls freedom of navigation operations in the South China Sea, challenging what it says are restrictions on innocent passage imposed by China and other claimants.

"On July 16, USS Benfold (DDG 65) asserted navigational rights and freedoms in the South China Sea near the Spratly Islands, consistent with international law," the U.S. Navy said in a statement.

China says it does not impede freedom of navigation or overflight, accusing the United States of deliberately provoking tensions.

Monday marked the sixth anniversary of a ruling by an international tribunal that invalidated China's sweeping claims to the South China Sea, a conduit for about $3 trillion worth of ship-borne trade each year.

China has never accepted the ruling.

China claims almost the entire South China Sea. Vietnam, the Philippines, Malaysia, Taiwan and Brunei all have competing and often overlapping claims.

China has built artificial islands on some of its South China Sea holdings, including airports, raising regional concerns about Beijing's intentions.