Six Chinese government ships temporarily cruised in the territorial waters of disputed Tokyo-controlled islands on Friday, Japan's coastguard said.
Four maritime surveillance ships entered the 12-nautical-mile zone around one of the East China Sea islands shortly before noon (0300 GMT) but moved out nearly two hours later, the coastguard said.
They were sailing near Uotsurijima, the main islet of the disputed chain called the Senkaku Islands in Japan and the Diaoyu Islands in China.
Then two fisheries patrol boats cruised within 12 nautical miles of Kubajima, another isle in the chain, for about 30 minutes, the coastguard said.
The six ships remained within 24-nautical-mile "contiguous" waters off either Uotsurijima or Kubajima at 7:00 p.m. (1000 GMT), a coastguard official said.
Chinese vessels have moved in and out of what Japan says is its sovereign territory over the last two months, since Tokyo nationalized some of the islands.
As well as the potential mineral reserves to which ownership of the islands grants access, both countries have considerable amounts of national pride at stake in the decades-old spat.
The dispute has hit the huge trade relationship between the two largest economies in the region. Senior representatives from both governments are reportedly readying for a third round of talks on the issue. (AFP)
