A U.S. business newspaper says that a Chinese group hacked into the computer files of America's largest corporate lobbying group.

The Wall Street Journal reported Wednesday that the Chinese hackers infiltrated computers at the U.S. Chamber of Commerce, which represents the interests of more than three million businesses of all sizes throughout the country. The newspaper said evidence shows that hacking occurred at least from November 2009 to May 2010, when it was discovered by the U.S. Federal Bureau of Investigation and then shut down.

The lobbying group said the hacking focused on four of its employees who worked on Asia policy and that six weeks of their email was stolen.

The newspaper said the hackers were part of a group suspected of having links to the Chinese government. The Chinese embassy in Washington dismissed the allegation that the hacking originated in China, saying it “lacks proof and evidence and is irresponsible.”