BEIJING -- China's Defense Ministry says a Chinese warship is assisting the U.S. Navy in its search for a sailor who is missing and may have gone overboard during operations in the South China Sea.

The ministry said in a statement Thursday that the People's Liberation Army Navy's guided-missile frigate Liuzhou is coordinating with the U.S. in the search for the sailor "in the spirit of humanitarianism."

The U.S. Navy's Pacific Fleet says the destroyer USS Stethem reported a man overboard around 9 a.m. Tuesday. Multiple searches of the destroyer were conducted but the sailor hasn't been found.

Get Breaking News Delivered to Your Inbox

China, which claims virtually all of the South China Sea, accused the U.S. in July of trespassing in its waters when the Stethem sailed within 12 nautical miles of Triton Island in the Paracel Group.

The operation was aimed at affirming the right to passage and challenging what the U.S. considers China's excessive territorial claims in the area. China sent ships to intercept the destroyer.

China has strongly objected to repeated freedom of navigation missions by the U.S. Navy in the South China Sea.

In June, a sailor believed to have fallen overboard from the USS Shiloh in the South China Sea was found hiding aboard the ship. That officer, Petty Officer 3rd Class Peter Mims, has been punished for abandoning watch and dereliction of duty.