Computer hackers infiltrated some Canadian government computer systems but were not able to access the classified data they were seeking, government officials.

Stockwell Day, president of the Treasury Board, which is a federal administrative agency, said the attacks were significant but that Canada's cyber security systems detected the intrusions and blocked them.

"I wouldn't say it's the most aggressive, but it was a significant one significant that they were going after financial records," said Day. "Every indication we have at this point is that our sensors and our cyber-protection systems got the alerts out in time, that the information doors were slammed shut."

The Canadian Broadcasting Corporation reported computers belonging to the Treasury Board and Finance Department were among the systems infiltrated in early January, along with Defense Research and Development Canada, which is a research agency within the Department of National Defense.

Jay Denney, a spokesman for Day, confirmed employee access to the Internet has been limited at the Treasury Board for the time being. He said the government "has plans in place to prevent, minimise and address the impacts of cyber threats."

The Finance department is preparing the federal budget, which will be delivered next month.

"Our government takes threats seriously and has measures in place to address them. The next phase of our economic action plan is still in development, and we have no indication that budget security has been compromised," Chris McCluskey, a spokesman for the minister of public safety, told The Associated Press.

Denney confirmed there are no indications that any data relating to Canadians was compromised.

Prime Minister Stephen Harper said yesterday that federal security agencies were working to deal with cyber threats.

"I can't comment on any specific reports," Harper said. "But this is an issue we are aware of and our security personnel are engaged in dealing with."

The CBC reported the cyber attacks were traced to computer servers in China, but no government official would confirm the origins of the attacks.

The report said hackers were using a technique known as spear phishing, which involves impersonating bureaucrats via their e-mail accounts to snoop around government computer systems and steal key passwords that unlock government data systems.