China says followed U.S. warship

Chinese authorities monitored, followed and warned U.S. warship USS Lassen as it "illegally" entered waters near disputed islands and reefs in the South China Sea on Tuesday, the Foreign Ministry said.

"China strongly urges the U.S. side to conscientiously handle China's serious representations, immediately correct its mistake and not take any dangerous or provocative acts that threat China's sovereignty and security interests," the ministry said in a statement on its website.

The patrol by the USS Lassen was the most significant U.S. challenge yet to 12-nautical-mile territorial limits China asserts around the islands in the Spratly archipelago and could ratchet up tensions in one of the world's busiest sea lanes.