Japan's Coast Guard on Monday released an edited version of video footage showing a clash between pro-China activists and its patrol ships near disputed islands earlier this month.

The move came as the government of Prime Minister Yoshihiko Noda declined a request from the Tokyo government to send a team of surveyors to land on the islands at the centre of a bitter territorial dispute with China.

The footage, originally several hours long but cut down to about 30 minutes, shows a clash between Japanese coastguards and pro-Beijing activists in waters near the uninhabited East China Sea archipelago -- called Senkaku in Japanese and Diaoyu in Chinese.

It shows Japanese patrol ships using water cannon on the Chinese boat with activists throwing objects at the coastguards, before five activists landed on one of the islands.

It was not clear from the footage what they were throwing but a coastguard official said "we later found bricks on the patrol ships."

The video also shows two patrol ships sandwiching the activists' boat to block its way, just before Japanese officials managed to get on board, the official said.

Tensions between Japan and China flared after five pro-Beijing activists landed on the islands. They and nine others, including two journalists from Chinese media, on the boat were arrested by Japanese police and later deported.

Just days later, Japanese activists and local legislators also landed on the Japanese-controlled islands, despite warnings not to do so by authorities.

Tokyo governor Shintaro Ishihara, well known for his nationalistic views, announced last week that a team of surveyors, biologists and local politicians would visit the disputed chain.

The central government on Monday turned down Tokyo's request for the team to land, angering Ishihara, who said the decision was "totally incomprehensible," quoted by Jiji Press.

Also on Monday, a car carrying the Japanese ambassador to China was targeted in Beijing by a man who ripped off the vehicle's Japanese flag, a foreign ministry official said.

The ambassador, Uichiro Niwa, was not hurt in the attack, the official said.

The Japanese embassy filed a protest with the Chinese foreign ministry and demanded such an incident is never repeated, the official said.