Three Chinese government ships on Thursday were plying waters around islands controlled by Tokyo and claimed by Beijing, the Japanese coastguard said.
The maritime surveillance vessels entered the 12-nautical-mile zone regarded as the territorial waters of Uotsurijima, one of the Senkaku islands, which China calls the Diaoyus, in the East China Sea shortly before 8.30 am, the coastguard said.
Ships from the two countries have for months traded warnings over intrusions into what both regard as sovereign areas as Beijing and Tokyo jostle over ownership of the strategically sited and resource-rich islands.
A territorial row that dates back four decades reignited last September when Tokyo nationalised three islands in the chain, in what it said was a mere administrative change of ownership.
Former Japanese prime minister Yukio Hatoyama came under fire this week after he said he understood China’s claim to the islands.
Hatoyama, whose stint in the top job is usually regarded as a bit of a disaster, told Hong Kong-based Phoenix Television it was “unavoidable” that China believed Japan “stole” the Senkaku islands.
Japan’s top government spokesman Yoshihide Suga on Wednesday declared himself dumbfounded over the remark.
Goshi Hosono, secretary-general of the centre-left Democratic Party of Japan which Hatoyama helped to found, said the remark was “extremely inappropriate” and urged him to reflect on what he said.