An American security firm said hackers working from China have broken into computers of oil companies in the United States, Taiwan and other countries.

The report by McAfee says hackers stole sensitive information about operations, finances and bidding for oil fields.

The report did not identify the companies but said the attacks began in November 2009 and targeted computers in the United States, Taiwan, Greece and Kazakhstan, AP reports.

Computer security consultants say China is a leading center for Internet crime including sophisticated industrial espionage aimed at major companies. The government has denied that it is involved.

Google Inc. closed its China-based search site last year after complaining about hacking attacks from China against its e-mail service.