Attorney-General Nicola Roxon has moved to ease community concerns over a controversial plan to store data about people's phone and internet use for up to two years.

Ms Roxon insists there would be strict privacy measures in place to make sure the information is only used by crime-fighting agencies when it is needed.

Under the plan, phone and internet companies will be required to keep logs of internet sites and phone calls made by their customers for several years instead of regularly deleting the data.

The idea is currently being considered by a parliamentary committee, and Ms Roxon says the Government is yet to make a final decision about whether to proceed.

But she appears to be lining up behind the plan, saying call charge records and mobile phone tower information is crucial to solving the 1994 murder of Sydney-based MP John Newman.

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"The intention behind the proposed reform is to allow law enforcement agencies to continue investigating crime in light of new technologies," Ms Roxon told a security in government conference.

"The loss of this capability would be a major blow to our law enforcement agencies and to Australia's national security."

The parliamentary committee assessing the proposed changes to national security legislation has received 177 submissions from government agencies, members of the public and privacy advocates.

Greens communications spokesman Scott Ludlam says Ms Roxon has effectively pre-empted the work of the committee and declared the Government's support for the controversial plan.

"The proposal is absolutely outrageous (and) I can't understand why the Attorney-General hasn't at least waited for the committee to do its work," Senator Ludlam told ABC News.

He says it would effectively mean the roll-out of real-time surveillance of everyone in Australia.

But Ms Roxon says there will be safeguards in place to make sure the information is not abused.

"It has always been a balancing act between providing proper protections for the community who expect to be safe (and) expect our law enforcement agencies to be able to do track down and prosecute those involved in criminal activity or those intent on causing harm," Ms Roxon said.

"But with that always comes proper oversight; how you make sure that we're not reaching too far into the private lives of Australians."

The Australian Federal Police are backing the proposal, saying the technological changes that have taken place in the past decade have increasingly undermined existing laws.

It says the data retention proposal would not give the agency new power, rather it would ensure existing capabilities are protected in a changing telecommunications environment.