Japan has confirmed that vessels carrying pipes are sailing in the East China Sea toward two gas fields at the center of an energy and border dispute between Japan and China, the trade minister said Friday.

Economy, Trade and Industry Minister Shoichi Nakagawa told a news conference after the day's Cabinet meeting that Tokyo received information Thursday that the ships are heading to the Tianwaitian and Chunxiao fields. He did not refer to the nationality of the vessels.

Japan has made an inquiry to China over the matter, but Beijing has yet to respond. Japan may lodge a formal protest, depending on the response, the minister suggested.