The Chinese Foreign Minister today denied his country is using the internet to spy on others and said China has itself been a victim of cyber-espionage.

Yang Jiechi said: “The Chinese government firmly opposes hacking attacks ... these are prohibited by law.”

Speaking at a press conference London with the Foreign Secretary David Miliband, Mr Yang added: “Actually a number of Chinese agencies have been attacked by hackers.”

The comments were made after The Times revealed that the Director-General of MI5 had sent letters to 300 executives and security chiefs at banks, accounting and legal firms warning them that Chinese state agencies were hacking into their systems and trying to steal confidential information.

A Chinese Foreign Ministry spokesman yesterday claimed that the report was slanderous and prejudiced and ignored the political, economic and social progress made by the country. China also alleged that the report was an attempt to put obstacles in the way of improved ties between Britain and China.

Gordon Brown is expected to make an official visit to Beijing in January. Mr Yang said he expected the trip to focus on “promoting world peace and security”.

The Times reported on Saturday that Jonathan Evans, the head of MI5, had written to businessmen warning them of industrial cyber-espionage that had been traced back to China. People who had seen the letter told The Times that the security forces believed that companies doing business in China were under particular threat from hackers.

The hackers are thought to include specialists with links to the People's Liberation Army (PLA). Hackers connected to the Chinese military have also been accused by computer experts of carrying out cyber attacks on the US Pentagon, the British Parliament and the German Chancellery.

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