Washington - Hackers in China broke through the computer defences of the US Chamber of Commerce last year and were able to access information about its operations and its 3 million members, the Wall Street Journal reported on Wednesday. The operation against the top American business lobbying group involved at least 300 internet addresses and was discovered and shut down in May 2010, the Journal reported, citing unidentified people familiar with the matter. The newspaper reported it was not known how much information was seen by the hackers, who may have had access to the network for more than a year before being discovered. The group behind the breach is suspected by the United States of having ties to the Chinese government, one of the sources told the newspaper. The FBI informed the Chamber of Commerce that servers in China were pilfering its information, the source said. The Journal quoted Chinese Embassy spokesperson Geng Shuang saying the allegation that the attack came from China “lacks proof and evidence and is irresponsible,” adding that the hacking issue should not be “politicised”. The Chamber of Commerce employs 450 people and represents business interests in Congress, including most of the largest US corporations. The newspaper reported that the emails revealed the names of companies and key people in contact with the Chamber, as well as trade policy documents, meeting notes, trip reports and schedules. “What was unusual about it was that this was clearly somebody very sophisticated, who knew exactly who we are and who targeted specific people and used sophisticated tools to try to gather intelligence,” the group’s chief operating officer, David Chavern, told the Journal. China is often cited as a suspect in various hacking attacks on US targets. In August, the Pentagon warned in a report to Congress that hacking from China could one day be used for overt military means.