But AFP Commissioner Tony Negus said yesterday he could ''live with'' a contentious government proposal to force telcos to keep it for two years.

''The two-year proposal … we could live with,'' he said. ''It certainly wouldn't be ideal, but we could live with [it].''

Commissioner Negus, New South Wales Police Commissioner Andrew Scipione and South Australian Police Commissioner Gary Burns gave evidence at a parliamentary inquiry yesterday on behalf of Australia's police commissioners, saying they wanted to be heavily involved in drafting controversial new national security laws.

But the men say their motives are ''pure'', and they simply want their crime-fighting tools to be brought into the 21st century.

Under the proposals put forward by the federal government, so-called ''metadata'' - which includes times, locations and durations of phone and internet communication - could be accessed by authorities with a warrant.

The new laws would allow authorities including police, the Australian Tax Office and Medicare to access data that telecommunications companies had been compelled to keep, up to two years after a call was made, or email sent.

At present it is up to the telecommunications companies to decide how long they keep such information.

Acting Victorian Privacy Commissioner Anthony Bendall said the proposed change ''turns the basic precepts of privacy on its head''.

''The idea that the state would be requiring private companies to keep data on private citizens, that is actually turning the private companies into agents of the state,'' he said.

Yesterday Mr Negus said police did not seek access to the content of Australians' emails or online chats, but strongly supported ''maintaining existing [warrant] capability in the face of changing technology''.

The police chiefs said the nation's police forces were struggling with telecommunications intercept laws written in 1979 that had been overtaken by technological advances.

Authorities are already able to access phone and internet data, including times, locations and durations of calls, without warrants, and did so more than 250,000 times in 2010-11.

The police commissioners said they wanted to be involved in drafting new reforms, or even new legislation, saying criminals were able to operate outside the reach of telecommunication laws and law enforcement agencies.

The controversial data retention proposals, outlined in a discussion paper circulated by Attorney-General Nicola Roxon, have come under fire from privacy and legal circles over fears that unreasonable amounts of data could be stored, and that there will be inadequate safeguards to protect personal information.