Japan arrested five activists from Hong Kong who landed on the Diaoyu Islands at around 5:30 p.m. local time on Wednesday on suspicion of illegal entry, according to police from Japan's Okinawa.

Two other activists who also landed on the islands returned to the fishing vessel, said the police.

"The five arrested may be transferred to the Immigration Bureau of Japan later and sent back to Hong Kong by the Immigration Bureau," a spokesman from Japan Coast Guard (JCG) told Xinhua.

The Japanese government summoned Chinese Ambassador to Japan Cheng Yonghua to the Foreign Ministry in Tokyo to lodge a protest, chief government spokesman Osamu Fujimura said.

Meanwhile, China's Foreign Ministry said Wednesday it will lodge a complaint with Japan after Japanese authorities arrested five Chinese activists who landed on the Diaoyu Islands in the East China Sea.

China has asked Japan to refrain from taking any action that could endanger the safety of the lives and property of Chinese citizens going to the Diaoyu Islands, Chinese Foreign Ministry spokesman Qin Gang said earlier in a press statement.

"China is paying close attention to the developments of relevant issues, and it has expressed its serious concerns over the issues to the Japanese side," Qin said, adding that China's position on the Diaoyu Islands issue remains "clear and resolute".

The Hong Kong fishing vessel carrying eight Chinese activists seeking to assert China's claim to the Diaoyu Islands departed from Hong Kong on Sunday, according to previous media reports.