An American company says at least 48 chemical and military-related companies have been targeted in cyber attacks traced to computers owned by a man in central China.

U.S.-based Symantec Corporation said the attacks targeted 29 chemical companies and 19 other companies, most of them based in the United States and Britain. It said the purpose of the attacks appeared to be industrial espionage.

Symantec said the attacks used innocent-seeming e-mails to place malicious software on computers at the target companies. It said the attacks were traced to a computer system owned by a man in his 20s who lives in the Chinese province of Hebei.

The security company said it could not tell whether the man was acting on his own or on behalf of someone else.

The Chinese government has repeatedly been accused of using computer hackers to steal industrial secrets and disrupt the activities of competitors. Beijing strongly denies the charges and says it is also the victim of computer hackers.

Symantec did not identify the targeted companies but said most are involved in manufacturing advanced chemical compounds with military applications.

It said the same computer servers were used earlier this year in attacks aimed at human rights groups and the automotive industry.