Three Chinese government ships sailed into waters around disputed islands controlled by Tokyo on Friday, for the first time since late May, Japan's coastguard said.

The Chinese maritime surveillance vessels stayed in the waters for about four hours, sailing out shortly before 2:00 pm (0500 GMT), the coastguard said.

They were spotted inside the 12-nautical-mile zone off the Senkaku islands, which China calls the Diaoyus, in the East China Sea shortly before 9:30 am (0030 GMT), said the coastguard.

Chinese government ships have frequently plied the contiguous waters -- a zone outside territorial waters -- near the disputed islands, but it was the first time they had entered Japanese-controlled waters since May 26, the coastguard said.

Ships from the two sides have been involved in a chronic stand-off as Beijing and Tokyo jostle over ownership of the strategically important 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.