LONDON—Amnesty International welcomed China's partial lifting of its Internet censorship system Friday in the run-up to the Beijing Olympics, but urged the authorities to go further and ease all restrictions.

China rolled back a few high-profile planks of its web censorship in an apparent effort to defuse an embarrassing dispute over media freedom ahead of the August 8-24 Games.

Journalists at the media center in Beijing found that a wide array of Internet sites were inaccessible, including Western news organizations and human rights groups like the London-based Amnesty.

But after talks between the International Olympic Committee (IOC) and Beijing authorities on Thursday, several sites were unblocked.

"We welcome the news today that the authorities have lifted blocks on our website in the Olympics media venues and possibly elsewhere in Beijing," said Roseanne Rife, Amnesty's Asia-Pacific program deputy director.

"However, arbitrary blocking and unblocking of certain sites does not fulfill the duty to comply with international standards of freedom of information and expression."

"Like the rest of the world, Chinese citizens have a right to access information and to express themselves on-line on all areas of legitimate public inquiry, including human rights.

"We continue to urge the authorities to ensure unfettered access to the Internet in line with official Olympic promises of 'complete media freedom' and international human rights standards."

Amnesty said The China Debate website it set up to encourage discussion about China's human rights record remained blocked.

The organization said strong public concern appeared to have played a part in China's decision to unblock some websites.

"Where silent diplomacy on human rights fails, strong public pressure can clearly have an effect," said Rife.

"We continue to urge the IOC and world leaders planning to attend the Games to speak out for human rights and on behalf of Chinese human rights activists who have effectively been silenced."