Beijing: China on Monday reaffirmed its sovereignty over the disputed islands in East China Sea, asking Japan to withdraw its fishing boats from the maritime territory, even as Japanese Foreign Minister has wrapped up his visit here, pledging warmer bilateral ties.

"China has indisputable sovereignty over the Diaoyu Islands that have been an inherent part of China since ancient times," Chinese foreign ministry spokesman Hong Lei said in a statement.

The issue apparently figured in the talks between Foreign Minister Takeaki Matsumoto and his Chinese counterpart Yang Jiechi.

"Any actions by the Japanese side in the waters around the Diaoyu islands are illegal and invalid," he said, noting that Beijing had lodged "solemn representations" with visiting Japanese Foreign Minister Takeaki Matsumoto, over fishing boats operating in the area.

The islets called Senkaku islands by Japan were currently under the administrative control of Japan and are jointly claimed by both the countries.

The countries experienced severe tensions last year over the arrest of a Chinese fishing trawler skipper by Japan.

Hong quoted Japanese media report saying that about 10 fishing boats belonging to a fishery cooperative in Ishigaki, Okinawa Prefecture, left a local port Sunday to operate in the waters of the Islands.

It is reported that the Japanese fishing boats have already withdrawn from the Diaoyu Islands waters, Hong said, without providing a time frame.