"An employee at NBN Co who took dozens of photos of secret documents while assisting the Australian Federal Police in raids of Labor offices has been forced to delete them.

The staff member, who was enlisted by the AFP as a "special constable" to help identify allegedly leaked documents, took 32 photos of confidential items during raids in Melbourne on Thursday.

It's understood the AFP instructed the staffer to take the photos of the documents - now sealed under a claim of parliamentary privilege - to send to other NBN Co employees.

In a letter to the AFP seen by AAP, Labor's lawyer Paul Galbally said he'd been advised the photos of the documents had been disseminated.

"This act was wrong and, amongst other things, clearly had the potential to undermine my clients' claim for privilege," the letter said.

Mr Galbally has been advised the photos were downloaded onto a USB and handed to the Senate Clerk, who also holds the sealed documents.

The photos have been deleted and cannot be retrieved, the letter said.

Police have been investigating the leaking of confidential documents about the national broadband network after it was referred from NBN Co last December.

The documents seized from the office of Labor senator Stephen Conroy and the home of an ALP staffer can't be analysed by police until the Senate decides if parliamentary privilege does apply.

The Senate won't sit until after the July 2 election.

In the letter, Mr Galbally asks AFP Commander Paul Osborne for an explanation as to why the photos were sent out by the staff member when a "clear claim for privilege had been made and acknowledged by officers present".

He also wants to know who authorised the staffer to take such action.

In a statement on Friday, NBN Co said staff had "followed and complied with instructions from the AFP at all times".

AFP commissioner Andrew Colvin earlier defended the AFP's independence amid Labor claims the Turnbull government played a part in the "extraordinary and unprecedented" raids during an election campaign.

No one in the government knew about the AFP investigation into the leaking of NBN documents until the raids began on Thursday, Mr Colvin said.

Opposition Leader Bill Shorten accused Prime Minister Malcolm Turnbull of being behind the decision to call in the investigators.

The leaks revealed massive cost blowouts and unacceptable delays with the NBN, he said, which had embarrassed Mr Turnbull - who was in charge of the project as communications minister before becoming prime minister.

The coalition could not distance itself from the actions of government-owned NBN Co, he said.

"This is about an arm of the government, the NBN, seeking an investigation to shut down the truth," he told reporters.

"It is inconceivable that this government business enterprise is acting like a sort of a rogue gunman unbeknown to government what they're doing."

Mr Turnbull hit back, accusing Labor of shamefully attacking the integrity of the AFP.

There is speculation there could be further raids involving media companies that published stories sourced to the leaked documents.

The warrants reportedly made reference to the ABC, The Australian, The Australian Financial Review and The Sydney Morning Herald.

AFP officers have interviewed a number of people at NBN Co's headquarters in Sydney.

An AFP spokesman confirmed the NBN staffer was "under the direction of AFP officers at all times during the search warrant".