The Australian Federal Police has searched the office of the senior Labor senator Stephen Conroy, in a move the Opposition says is "extraordinary and unprecedented" during an election campaign.

Key points: Senator Stephen Conroy's office, home of Labor staffer raided

Senator Stephen Conroy's office, home of Labor staffer raided Tony Burke says NBN documents were leaked

Tony Burke says NBN documents were leaked Malcolm Turnbull says the incident a matter for the federal police

But the Prime Minister has rejected any suggestion of Government interference, saying the AFP operates "entirely independently of the Government".

Labor says the searches on Senator Conroy's Melbourne office and the home of a Labor staffer in the suburb of Brunswick are connected to documents leaked from National Broadband Network (NBN).

It is understood officers raided the home of a staffer of Opposition communications spokesman Jason Clare.

The AFP this morning issued a statement confirming the searches, which it said were "concerning allegations of the unauthorised disclosure of Commonwealth information".

"This investigation has been undertaken independent of government, and decisions regarding yesterday's activity were made by the AFP alone," the statement said.

Sorry, this video has expired Jason Clare responds to AFP raid on Labor figures

Mr Clare criticised the raids, saying the NBN had become "a mess" under Malcolm Turnbull.

"Really [Mr Turnbull] needs to be focused on fixing the mess that he has made of the NBN," he said.

"You've got police apparently investigating where these leaks have come from. What is next? Are they going to raid The Daily Telegraph? Raid the AWN newspaper? Raid the Sydney Morning Herald? Raid the ABC and arrest people in those news organisations who reported these leaks?"

Shadow attorney-general Mark Dreyfus described the events as "extraordinary and unprecedented".

"The Government has a great deal of explaining to do," he told Lateline.

"All Australians are right to be concerned about the appearance of a raid being conducted on a Labor senator's office and on the homes of Labor staffers in the second week of a campaign."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 7 minutes 14 seconds 7 m Mark Dreyfus says the raids during an election campaign were unprecedented

Mr Dreyfus questioned whether proper procedure had been followed, given the Government is now in caretaker mode, and he suggested there was a double standard.

"It's vitally important that the Australian Federal Police and a national government at all times conduct themselves in a manner which builds confidence in our police forces and our security agencies," he said.

"There have been more than 20 serious national-security-related leaks under this Abbott-Turnbull Government, and not one of them has resulted in an AFP investigation."

The ABC understands that once the search on Senator Conroy's office was underway, Opposition Leader Bill Shorten was briefed by the AFP Commissioner Andrew Colvin, immediately after Justice Minister Michael Keenan was informed.

It is understood that is the first the Government knew of the investigation, and that the matter was referred to police by NBN.

The NBN confirmed its involvement in the investigations in a statement this morning but would not comment further.

The ABC understands Bill Shorten was briefed on the search by the AFP Commissioner. ( ABC News: Pat Stavropoulos )

'The AFP is an entirely independent organisation'

Mr Shorten has sought to tie the events to the Prime Minister.

"We'll have more to say in coming days, it's an extraordinary development," he told reporters in western Sydney.

"It relates to Mr Turnbull's time in charge of the NBN and the extraordinary blowout of costs and huge delays in the implementation of NBN and millions of Australian households not getting what was promised."

Sorry, this video has expired Tony Burke and Mathias Cormann discuss the AFP raids

As he left the same event as Mr Shorten, Mr Turnbull said it was entirely a matter for the AFP.

"They operate entirely independently of the Government and so this is a matter for the AFP, the Labor Party know that as well as you and I do," Mr Turnbull said.

Treasurer Scott Morrison and Finance Minister Mathias Cormann also stressed the independence of the AFP.

"The AFP is an entirely independent organisation that makes their own judgements on these things," Mr Cormann said.

Documents from NBN Co marked "commercial in confidence" were first published by Fairfax in February, but the AFP confirmed the leaks had been referred to them by NBN Co three months earlier.

They referred to a "critical bottleneck" in the design phase of the broadband network.

On the day they were revealed, NBN Co said it was confident it would meet its rollout targets, and that the project would come in on budget.