China is being blamed for a major cyber attack on the computers at the Bureau of Meteorology, which has compromised sensitive systems across the Federal Government, reported ABC.

The ABC has been told it will cost millions of dollars to plug the security breach, as other agencies have also been affected. The bureau owns one of Australia’s largest supercomputers and provides critical information to a host of agencies.

Its systems straddle the nation, including one link into the Department of Defence at Russell Offices in Canberra.

But the ABC has been told this is a “massive” breach and one official said there was little doubt where it came from.

“It’s China,” he said.

The motivation for the attack on the bureau could be commercial, strategic or both.

The bureau is a critical national resource and another state would place a high value on its intellectual property and scientific research.

In the event of a conflict, compromising Australia’s ability to accurately forecast weather would affect the operation of military and commercial aircraft.

In March, the Bureau’s chief executive Robert Vertessy told Radio National that his agency had evolved “from what was once just a straight weather service to what I would call now a more broad-based environmental intelligence agency”.

It provides weather and climate forecasting, tsunami warnings, tide predictions, water resources and even space weather.

There is no clear picture yet how much the breach will cost to fix or how long it will take but the critical nature of the bureau’s services means its systems cannot be switched off for repair.

“It could take years and cost hundreds of millions of dollars to fix”, a source told ABC.

The Bureau of Meteorology refused to confirm the reported breach to Fairfax Media, instead pointing to a statement on its website.

“The Bureau does not comment on security matters,” the statement said.

“Like all government agencies, we work closely with the Australian government security agencies.

“The Bureau’s systems are fully operational and the Bureau continues to provide reliable, on-going access to high-quality weather, climate, water and oceans information to its stakeholders.”

The Department of Defence said that as a matter of principle and long-standing practice the government did “not publicly discuss specific cyber activities or incidents”.

Prime Minister Malcolm Turnbull’s office also declined to confirm the reported breach.

“It is not the policy or practice of the government to comment on specific cases,” the Prime Minister’s spokesperson said.

“The Bureau will continue to provide quality reports and warnings and weather information to the community and its stakeholders.

“As outlined in the inaugural Australian Cyber Security Centre Threat Report, the number, type and sophistication of cyber threats to Australia is increasing.

“There is a range of adversaries motivated to target our networks, including state-sponsored actors and serious and organised criminals.

“The government takes any cyber attacks seriously and is currently reviewing its cyber security policy.

“The government will soon consider the outcomes of the Cyber Security Review and then set a date to release a new Cyber Security Strategy.”