SHANGHAI: China lodged a formal protest with Japan on Saturday over plans by a Japanese nationalist group including lawmakers to hold a ceremony commemorating Japanese dead from World War Two near disputed islands in the East China Sea this weekend, state news agency Xinhua said.

The group of more than 100 people travelling in a flotilla of boats is expected to arrive near the islands on Sunday morning. Japan’s government has denied the group permission to land on the islands.

The report said China had lodged “solemn representations” with Japan over the matter, a term official media uses to indicate a particularly high level of diplomatic opposition.

Foreign Ministry spokesman Qin Gang said that China had urged the Japanese government to immediately “stop the action that seeks to undermine China’s territorial sovereignty” over the rocky, uninhabited isles known as the Senkaku in Japan and the Diaoyu in China, Xinhua said.

Japan on Friday sent home Chinese activists who were detained on Wednesday after landing on one of the islands.

China welcomed the return of the activists, but also warned its neighbour against any further escalation in tension.

Japan occupied much of China during the war and colonised the Korean peninsula, resulting in territorial disputes that continue to dog relations with its neighbours nearly seven decades after the end of World War Two.