The boat carrying the Hong Kong-based Action Committee for Defending the Diao-Yu Islands was sailing to an uninhabited group of islands which has become a focus for tension between nationalists from China and Japan, and a scene of annual demonstrations.

Activist David Ko speaking about the protest from Hong Kong

A spokesman for the group said their protest boat was hit by several Japanese military vessels on Wednesday morning local time, when it was sailing in disputed waters.

He said the boat, carrying more than 20 Hong Kong protestors, sustained damage but was still seaworthy. No one was injured.

The group is still planning to join Taiwanese activists in attempting a symbolic landing on the islands, although that may be prevented by the Japanese presence.

Activist David Ko, monitoring events from Hong Kong, said the sovereignty of the islands was not the only subject of their protest.

"Other issues are also involved, including requests to the Japanese that they should apologise to the Chinese people for the crimes they committed during the Second World War," he said.

Two years ago, one Hong Kong protestor drowned when he jumped into the sea during a confrontation with Japanese patrol boats.