Microsoft is under the spotlight over its blocking of a prominent Chinese Internet blogger, in the latest case of a major Western technology firm helping Beijing curtail free speech.

The MSN Spaces-hosted web log, or blog, belonging to Beijing-based media researcher Zhao Jing was closed down this week after he posted articles critical of a management purge at the Beijing News daily.

"I posted three posts about the Beijing News and all posts and articles were deleted inside China," Zhao, who uses the pen name Michael Anti, told the XFN-Asia news service this week.

"MSN Spaces (has) now deleted all of my articles and I have no backup and I'm very angry."

Microsoft had already faced intense criticism when it was revealed last year that its Chinese blogging service restricted the entry of sensitive terms such as "demonstration", "democratic movement" and "Taiwan independence".

The MSN Spaces operation, a Microsoft joint venture with state-owned Shanghai Alliance Entertainment, is the top blog hosting service in China.

Microsoft this week defended its latest action, releasing a statement saying it was acting in line with global laws when it deleted the web blog.

"In line with Microsoft practices in global markets, MSN is committed to ensuring that products and services comply with global and local laws, norms, and industry practices," the company said.

"Most countries have laws and practices that require companies providing online services to make the Internet safe for local users. Occasionally, as in China, local laws and practices require consideration of unique elements."

Reports of the shutdown of Zhao's blog have generated a groundswell of criticism of Microsoft on the Internet - including from former CNN Beijing bureau chief Rebecca MacKinnon on rconversation.blog.com.

"The behavior of companies like Microsoft, Yahoo! and others - and their eager willingness to comply with Chinese government demands - shows a fundamental lack of respect for users and our fundamental human rights," MacKinnon said on her blog.

"Microsoft, Yahoo! and others are helping to institutionalize and legitimize the integration of censorship into the global IT business model."

Yahoo! came under fire for turning over to Chinese police the e-mail records of journalist Shi Tao, after he circulated on the Internet a government order to suppress all media commemorations of the 15th anniversary of the 1989 crackdown of the Tiananmen democracy protests.

The disclosure led to Shi being jailed last year for 10 years.

US giant Google has also been accused of censoring its Chinese language search engine, while Cisco Systems Inc and other firms have been accused of helping set up what has come to be known as the "Great Firewall of China," one of the world's most advanced systems of censoring information on the Internet.

US Verso Technologies also said in November last year it had sold software to a major, but undisclosed, Chinese telecoms firm that will allow China to block popular free Internet telephone services such as Skype.