China has overlapping claims with Vietnam, the Philippines, Malaysia, Taiwan and Brunei in the South China Sea, through which $5 trillion in ship-borne trade passes every year.
Its land reclamation work in the sea has raised concern in the region about its intentions, and last week a U.S. warship sailed within 12 nautical miles of one of Beijing's man-made islands in the contested Spratly archipelago.
Speaking at the National University of Singapore, Xi said freedom of passage in the South China Sea has never been a problem and will never be a problem.
Asian countries should resolve security problems using peaceful methods, he said.
