'It's a very unfortunate development,' said Ed Black, president of the Computer and Communications Industry Association.

'This is clearly an escalation of attempts to limit access and the freedom of the Internet,' he told AFP. 'It has economic and trade as well as cultural and social ramifications.' Mr Black said the Chinese move smacked of an attempt to 'not only control their own citizens access to the Internet but to force everybody into being complicit and participate in a level of censorship.'

'I hope the US Trade Representative, the State Department and other agencies of government will try to step up and reverse the decision,' he said.

Two of the biggest US PC manufacturers, the Palo Alto, California-based Hewlett-Packard and the Round Rock, Texas-based Dell, told AFP they were seeking more information about the Chinese move.

'HP is working closely with trade industry associations and ITI (Information Technology Industrial Council) to seek additional information, clarify open questions and monitor developments on this matter,' a spokeswoman said.

'We are aware of the policy,' Dell said in a statement. 'Along with the rest of the industry, and relevant trade associations, we are reviewing it and will work with government officials and others to understand its application.' Microsoft, which provides the Windows software that runs most of the world's PCs, said it planned to issue a statement later in the day.

The head of a software developer involved in devising the programme confirmed the report to AFP, saying it was aimed at protecting people from pornography.

'The software will be provided to consumers in new PCs and they have the option to install or not to install it,' said Bryan Zhang, chief executive of Jinhui Computer System Engineering Co. -- AFP