China on Thursday rejected as "groundless" reports suggesting it was behind an unprecedented cyberattack on the Canadian government that penetrated two key agencies and forced them offline.
The attacks, first detected in January, have been traced to servers in China, Canadian broadcaster CBC reported Wednesday, quoting government sources.
CBC said it was unclear whether the attackers were Chinese or simply other nationals who used China-based servers, but another Canadian channel, CTV, reported they were "Chinese government hackers".
A Chinese government spokesman denied involvement by Beijing.
"The allegation that the Chinese government supports Internet hacking is groundless," foreign ministry spokesman Ma Zhaoxu told reporters during a regular briefing.
"The Chinese government attaches importance to the safety of computer networks and asks computer and Internet users to abide by laws and regulations."
The hackers penetrated computer systems at the Finance Department and the Treasury Board, according to CBC.
They also infiltrated computers in the offices of senior government officials in a bid to steal passwords providing access to key government data.
Canada's government has declined to comment in detailed on the issue.
The nation's Treasury Board issued a brief statement saying it had detected an "unauthorized attempt to access its networks".
CBC News cited "highly placed sources" in Prime Minister Stephen Harper's government as saying that the cyberattacks, first detected in January, were traced to computer servers in China.
Several governments have pointed to the growing threat of Chinese espionage online.
Last week, US computer security firm McAfee said hackers from China had penetrated computer networks of global oil companies, stealing financial documents on bidding plans and other confidential information.
In January 2010, Google said it had fallen victim to attacks by China-based cyber spies apparently intent on hacking the Gmail accounts of Chinese human rights activists.
China consistently rejects charges it is behind cyber-spying.
"The Chinese government is firmly opposed to hacking and other criminal activities targeting computer networks and fights against such activities," Ma said.