By Wang Zhaokun

China's Ministry of Foreign Affairs said Friday that the leak of a video footage showing the collision between a Chinese fishing boat and two Japanese Coast Guard vessels off the Diaoyu Islands cannot conceal Japan's unlawful actions.

"I would like to reiterate that the Japanese patrol boats had disturbed, driven away, intercepted and surrounded the Chinese fishing boat, which led to the collision," foreign ministry spokesman Hong Lei said. "The so-called video cannot change the fact and cannot conceal the unlawfulness of the Japanese action."

Ma Zhaoxu, another spokesman of the ministry, said earlier that the Diaoyu Islands have been an integral part of Chinese territory since ancient times, and Japan's illegal actions have severely infringed on China's sovereignty and Chinese fisher-men's rights and interests.

The Japanese Coast Guard has begun an investigation into a leak of the video clips that appeared on YouTube on Friday.

Japanese authorities have confirmed that the leaked video footage is identical to what the Japan Coast Guard recorded during the incident, the evening edition of the Yomiuri Shimbun reported Saturday.

The Kyodo News Agency reported that officials have begun to question the employees responsible for editing and storing the footage.

The leak of the footage has raised concerns of rekindled tensions between China and Japan, as Japanese Prime Minister Naoto Kan will host the Asia-Pacific Economic Cooperation summit in Yokohama next week.

It remains unclear whether Chinese President Hu Jintao will go to the summit and hold talks with Kan.

Beijing and Tokyo were embroiled in a series of diplomatic spats after the September collision and Japan's detention of a Chinese trawler captain.

Chinese Vice Foreign Minister Cui Tiankai, a former ambassador to Japan, called Friday for Japan's "responsible" action to bolster relations.

"The two governments have agreed that we want to build a strategic relationship of mutual benefit. This is where we should work harder," Bloomberg quoted Cui as saying.

"Whatever the details of the collision were, China's sovereignty over the Diaoyu Islands cannot be changed," Feng Zhaokui, a researcher at the Institute of Japanese Studies under the Chinese Academy of Social Sciences, told the Global Times.

"However, the leak of the video might further spur Japan's nationalism, which is not conducive to the improvement of ties," he added.

Feng's remarks came after around 4,000 Japanese staged an anti-China demonstration in Tokyo on Saturday.

Separately, public support for Kan's cabinet plunged to 32.7 percent this month, down 14.9 percentage points from the previous survey in early October, an opinion poll by the Kyodo showed Sunday.

Some 74 percent of respondents disapproved of the cabinet's foreign policies, the poll showed.

Agencies contributed to this story