BEIJING, Jan 7 - China on Thursday said it was unhappy at reported Japanese plans to build a port on a remote Pacific atoll, which Beijing fears Toyko will use to stake a claim to a large swathe of ocean as an exclusive economic zone.

Okinotori, also known as Douglas Reef or Parece Vela, is some 1,700 km (1,050 miles) south of Tokyo.

Japan has already built facilities such as a lighthouse there, and poured in concrete to make sure the atoll does not slip totally beneath the waves.

China has said previously that the atoll does not meet internationally recognised criteria to be classed as an island, making claims to the waters and continental shelf surrounding it invalid.

Japan's Kyodo news agency said this week that the transport ministry had asked for funding to build a port on Okinotori to help with exploration for resources in the area.

But Chinese Foreign Ministry spokeswoman Jiang Yu said the atoll could not be the basis for any territorial claims.

"Building infrastructure cannot change its legal position,"she told a regular news briefing in Beijing.

What Japan was trying to do "does not conform with international maritime law and has an effect on the interests of the international community".

Okinotori lies strategically about halfway between Guam, site of a large U.S. military base, and Taiwan, the self-ruled island China considers its own, to be reclaimed by force if necessary.

China and Japan have also been involved in a long dispute over a tiny group of islands in the East China Sea, known as Senkaku in Japan and Diaoyu in China.