The head of Britain's domestic spy agency has warned that China is spying on the computer systems of British corporations, a newspaper reported Saturday. The Times said MI5 chief Jonathan Evans sent a letter this week to 300 executives and security chiefs at banks, accountancies and legal firms, warning them that they were under attack from "Chinese state organizations" over the Internet. The newspaper said the letter had also been posted on a secure section of the Web site of the government's Centre for the Protection of the National Infrastructure. It included ways of identifying Chinese "Trojans," software designed to hack into a computer network and feed back confidential data, the paper said. The government Home Office, which oversees MI5, said it would not comment on private correspondence. China, with 140 million Web users, is a major center of Internet hacking, and many in the West suspect government involvement. Computer experts have blamed hackers linked to the Chinese military for cyber-attacks on the US Pentagon, the British Parliament and the German chancellery, although Western governments have been reluctant to accuse Beijing outright. British Prime Minister Gordon Brown said last week that he would make his first visit to China as premier in January.