China asked Japan to immediately stop all acts that harm China's territorial sovereignty, Foreign Ministry spokesman Hong Lei said late Saturday, after some Japanese landed on the Diaoyu Islands.

Hong said the Japanese landed on the Diaoyu Islands Friday evening with the excuse of preventing Taiwanese activists from landing on the islets.

"It is a severe infringement upon China's territorial sovereignty, and the Chinese government has lodged solemn representations and strong protests to the Japanese side," Hong said in a statement.

China will continue to take measures to firmly safeguard its territorial sovereignty over the Diaoyu Islands, Hong said.