Australia's spy agency ASIO has established a 'cyber' intelligence unit to counter possible terror attacks on computer systems from abroad, Attorney-General Robert McClelland said.

McClelland revealed the group's existence on Thursday, telling a dinner in Canberra that it followed ASIO's close cooperation with other agencies tasked with dealing with national computer emergencies.

"For this reason, ASIO has also established a specialist cyber investigations unit to investigate and provide advice on state-sponsored cyber attack against, or involving, Australian interests," he said.

It is understood the team has been operating since the second half of 2010.

The attorney-general said while traditional espionage also still posed risks, "the explosion of the cyber world has expanded infinitely the opportunities for the covert acquisition of information by both state and non-state actors."

"As these attacks can be staged from anywhere in the world, they can infiltrate the control systems of critical infrastructure, be activated remotely, causing damage and mayhem to our technology-dependent lives," he said.

McClelland noted the threat "posed by those using the Internet as a modern espionage tool with the potential to facilitate access to large volumes of sensitive government and commercial information."

He cited a cyber breach of the Dalai Lama's office and a serious cyber attack on Estonia in 2007 as examples of the need for action.

"These attacks and the threat to critical infrastructure such as banking, telecommunications and government systems is not something we can be complacent about," he said.