Japan's action on Diaoyu Islands 'invalid'

China said on Tuesday that any unilateral action taken by Japan about the Diaoyu Islands and its affiliated isles is invalid.

The remarks came after Japanese Chief Cabinet Secretary Osamu Fujimura said that the government on Monday had registered the north island, one of the four islands near the Diaoyu Islands in the East China Sea, as a national asset.

Earlier this month, Tokyo formally named four islands, three of which are owned by individuals, Kyodo News reported.