June 22 (UPI) -- China condemned a Japanese decision to rename an area that included the disputed Senkaku or Diaoyutai Islands, calling the move a "serious provocation."
Beijing foreign ministry spokesman Zhao Lijian said Monday at a regular press briefing the "renaming attempt" by Japan's Ishigaki city assembly is an illegal act that has no validity.
On Monday, the city assembly in Okinawa had passed a bill to rename an administrative area that includes the territory in the East China Sea, Kyodo News reported. Ishigaki Mayor Yoshitaka Nakayama had submitted the bill after Japanese boats were reportedly chased by Chinese patrol boats in Japan-claimed waters, according to the report.
The city agreed to change the administrative area's name from Tonoshiro to Tonoshiro Senkaku. The islands are claimed by Beijing and Taipei.
The city said the renaming would take effect on Oct. 1, and is aimed at "resolving administrative confusion between a place in downtown Ishigaki which is also called Tonoshiro."
In Beijing, Zhao said the Diaoyutai Islands have long been China's territory.
"China's determination and will to protect its territorial and sovereign rights remain unchanged," the Chinese spokesman said. "The attempts by the Japanese side do not change the fact that the Diaoyutai Islands belong to China."
China could be stepping up operations near the disputed territory, according to Kyodo. Four Chinese Coast Guard vessels were detected Monday in waters near the islands for the 70th consecutive day, the report says.
China's Coast Guard confirmed deployment on Monday and said its Shoushi-II class Haijing 2502, a patrol cutter weighing 5,500 tons, was on duty in an area near the islands.
Earlier this month, the Yomiuri Shimbun reported China is pursuing an amendment to the law that would allow its Coast Guard to receive instructions from Beijing's military during wartime.
The U.S. Department of Defense has previously said the Senkakus are covered under the U.S.-Japan Security Treaty.