BEIJING - Tokyo is planning to name 39 uninhabited islands, including several adjacent islets of the Diaoyu Islands, Japan's Chief Cabinet Secretary Osamu Fujimura said on Monday at a news conference.

The claim sparked concerns again on the lingering territorial dispute between China and Japan.

The Japanese government is working with the Geospatial Information Authority of Japan (GSI) to investigate seven unnamed adjacent islets of the Diaoyu Islands, Japan's Fuji Television said on Monday.

The Cabinet Secretary said the 39 islands are among the cardinal points selected by the Japanese government to help define its so-called exclusive economic zone (EEZ), according to Japan's Sankei Shimbun newspaper's website.

"The names (of the islands) will be finally decided within the year," he said. The government will reportedly determine the guidelines of naming the islands in March.

On Monday, Chinese Foreign Ministry spokesman Liu Weimin said that the Diaoyu Islands and adjacent islets have been an inherent territory of China since ancient times, over which China has "indisputable sovereignty".

"Our determination to protect China's sovereignty over the Diaoyu Islands is unremitting," Liu said.

After deciding the final version of the names, GSI and Japan's Coast Guard will put the names on the updated version of related maps, according to Sankei.

The naming of the islands is aimed at helping Tokyo to lay claim on its EEZ and "enhancing control" on the islands, Fuji TV reported.

"Fujimura's claim is casting a shadow on the warming China-Japan ties, especially against the backdrop of this year's 40th anniversary of the normalization of bilateral diplomatic relations," Feng Zhaokui, a researcher with the Institute of Japanese Studies of the Chinese Academy of Social Sciences, told China Daily.

China and Japan normalized diplomatic relations in 1972. During Japanese Prime Minister Yoshihiko Noda's state visit to China in December, leaders from both sides vowed to reinforce the strategic, mutually beneficial relationship.

Both sides agreed to mark this year as the year of "friendship and civil exchanges", featuring a series of commemorative events to strengthen public diplomacy.

Tokyo and Beijing are expected to take this year as a perfect opportunity to mark the anniversary, which serves both sides' overall interest, Feng said. "It is unwise to resort to tricks to sacrifice the overall interest for the interest of a certain group."

However, some Japanese politicians have been attempting to resort to territorial disputes to overshadow the existing good will from both countries. Four right-wing city assembly members of the Ishigaki city assembly in Okinawa Prefecture of Japan landed on an islet of the Diaoyu Islands on Jan 3. Beijing lodged a solemn representation and a strong protest.