The Canadian government was hit by an unprecedented cyber attack from Chinese-based computers last month that penetrated two key economic ministries, the Canadian Broadcasting Corp reported on Wednesday.
The CBC cited sources as saying the hackers broke into computer systems at the Finance Department and Treasury Board. Once the attack was detected, Internet access in both ministries was cut off.
The Finance Department is preparing the federal budget, which will be delivered next month.
The CBC said the hackers had apparently managed to take control of computers in the offices of senior government executives as part of a scheme to steal the passwords that unlock entire government data systems.
A spokesman for Treasury Board Minister Stockwell Day said officials had detected an unauthorized attempt to access the ministry's computer networks.
There are no indications that any data relating to Canadians was compromised, he said in an e-mail. He did not say whether the attacks had been traced back to Chinese servers, as the CBC reported.
No one from the office of Finance Minister Jim Flaherty responded to a request for comment.
Chinese Foreign Ministry spokesman Ma Zhaoxu denied there was a China link to the hacking.
What you mentioned is purely fictitious and has an ulterior motive, he told a regular news briefing in Beijing when asked about the accusations.
China attaches great importance to computer security and consistently opposes and cracks down on hacking activities according to relative laws and regulations, Ma added. Hacking is an international problem and China is affected also.
Canada's spy service complains regularly about what it says is industrial espionage by China and other states.
U.S. cables released by WikiLeaks show diplomats blaming China for hacking into Google systems that prompted the Internet giant to pull back from mainland China.
In 2009, The Wall Street Journal said cyber spies who appeared to be based in China had breached the Pentagon's Joint Strike Fighter project.
The CBC story comes at an awkward time for Canada's minority Conservative government, which has markedly toned down its criticism of China's human rights record as it tries to boost bilateral trade ties.