Malcolm Turnbull has emerged to back the Government's proposed new anti-terrorism laws, despite his anger over being sidelined over the plans.

The Communications Minister was not part of this week's National Security Committee meeting which gave in-principle agreement to controversial data retention plans.

The ABC understands he is angry he did not know about the plan before reading about it in a newspaper on Tuesday.

The former technology executive had been missing over the past few days while Prime Minister Tony Abbott and Attorney-General George Brandis struggled to publicly explain the technical details of proposed changes.

Senator Brandis ended up creating more confusion when he tried to clarify the use of metadata, while Mr Abbott did not help matters by indicating an internet user's browsing history would be included under the proposal.

Mr Turnbull is now being included in the strategy for mandatory data retention and says the policy needs to be "explained and justified".

"Metadata is a term that can mean different things to different people," he told Bloomberg TV.

"It is not the content of the telephone call. It is details about who called whom, where and when. That material has always been retained, originally for billing purposes, but is very important potential information to [be] accessed by security services and police services in the appropriate manner."

The Communications Minister says he is working closely with the Attorney-General to review arrangements for mandatory data retention.

He admits the proposals need to be justified.

"So what we have to do is get to the end of our consultation, conclude the very clear parameters of our policy, and then explain it and justify it," he said.

Mr Turnbull says the commentary has got ahead of the policy.

"There is a lot of speculation about what this might involve... We are in a process of consultation and engagement," Mr Turnbull said.

Brandis 'a walking disaster' says Labor

Labor's shadow attorney-general, Mark Dreyfus, says Senator Brandis is out of his depth.

"This Attorney-General, Senator Brandis, is a walking disaster," he said.

"The Prime Minister should be thinking about getting someone in the portfolio who actually understands about the issues that he is meant to be managing, perhaps someone like Malcolm Turnbull."

What the Government says about 'metadata' and 'content' For web browsing, "content" is anything user generated, e.g.: typing in a URL, clicking through to links or a Google search.

For web browsing, "content" is anything user generated, e.g.: typing in a URL, clicking through to links or a Google search. "Metadata" is information the system automatically puts in around the user-generated content, e.g.: IP addresses, number of visits to a site and length of time on a page.

"Metadata" is information the system automatically puts in around the user-generated content, e.g.: IP addresses, number of visits to a site and length of time on a page. An IP address viewed in the metadata would show a person visited a certain website, but would not show what specific pages they visited there, if they wrote anything there or viewed videos.

An IP address viewed in the metadata would show a person visited a certain website, but would not show what specific pages they visited there, if they wrote anything there or viewed videos. Currently, authorities can request access to metadata from telcos/ISPs, but they require a warrant for access to "content". Read the full explanation

The Opposition backs the principle of stronger security, but is concerned about privacy implications.

In Government, Labor drafted, but dumped, data retention plans for telecommunications companies.

Some internet service providers have complained the proposal will drive up costs.

Labor is calling it an internet tax.

Turnbull warns data retention could be costly

Mr Turnbull says the issue of cost has not been sorted out yet, but he is warning it could be "significant".

"Is there going to be a cost? If, for example, the outcome of this is no more than there will be a law that states that telcos should retain the type of data that they are currently retaining anyway, then there is no additional cost, or somewhere between no cost and very little cost," he said.

"If on the other hand, telcos are required to store and to record, store and make accessible new classes of data in large volumes then there would obviously be a significant cost.

"And then you have to go to the question of who should bear that cost."

Labor is focusing on Senator Brandis, who it says must step up his game.

"I have to say, that keeping Australians safe is simply too important to be left to someone like Senator Brandis who clearly does not understand the basics of their own portfolio," Mr Dreyfus said.

Deputy Greens leader Adam Bandt agrees.

"If I was George Brandis I would be having a serious think at the moment about falling on my sword," he told Sky News.

"He is certainly not an asset for this government and he is certainly not an asset for the Australian people."