Immigration Minister Peter Dutton should consider resigning over fresh allegations Australian-paid security guards filmed and photographed Greens senator Sarah Hanson-Young inside her hotel room during a covert spying operation, party leader Richard Di Natale says.

The Greens have called for a federal police investigation into the incident allegedly perpetrated by staff from Wilson Security, the subcontractor that oversees security at the Australian-run asylum seeker camp on Nauru.

Senator Di Natale on Friday said Senator Hanson-Young's movements were tracked and "she was photographed and filmed inside her hotel room" during a visit to the island in December 2013.

A Greens source said several people approached the party to disclose the information.

As Fairfax Media reported in June, private security guards on Nauru allegedly ran a secret surveillance operation on Senator Hanson-Young, an outspoken opponent of immigration detention.

The Wilson guards alleged she was covertly followed and her hotel was watched in a secret operation known as "Raven".

When the allegations first surfaced, Mr Dutton rejected them as "complete nonsense" and described Senator Hanson-Young as an "embarrassment to the country".

Wilson Security later apologised to the senator for spying on her, however Mr Dutton has not withdrawn the comments.

On Thursday night the ABC reported that former guards alleged up to eight members of the security company's Emergency Response Team tracked Senator Hanson-Young throughout her three-day visit to Nauru.

The former guards said orders were made to follow and photograph the senator and make notes on who she met and when.

They also claimed the senator's room number at the Menen Hotel and her car registration details were given to those taking part in the spy operation.

The guards alleged once the operation was uncovered, those involved were ordered to shred reports and pages from their notebooks.

Wilson Security would not comment on claims Senator Hanson-Young was photographed inside her hotel room.

In a statement on Friday, the company said it "categorically" rejected the claims made on the ABC, adding the allegations were anonymous and "we stand by our sworn testimony given to the Senate inquiry".

The allegations on the ABC, and those by Senator Di Natale, contradict evidence Wilson Security officials supplied to a Senate inquiry into conditions on Nauru.

The company's submission stated it "strongly rejects the allegation" that it organised a team to spy on the senator, saying some employees went to Senator Hanson-Young's hotel, primarily to ensure her "security".

The company's Southern Pacific executive general manager John Rogers also told the inquiry in June that the surveillance extended only to two staff sent to watch the hotel car park on one night.

The guards who spoke to the ABC accused their former employer of giving misleading evidence to Parliament - an act that could be considered contempt of the Senate.

Senator Di Natale said the spying allegations were extremely serious and Mr Dutton must ensure a full police investigation and departmental review. The Greens have also written to the Australian Federal Police to request an investigation and Senator Hanson-Young is considering legal action.

Senator Di Natale said if police did not investigate, Mr Dutton should "consider his position".

"Can you imagine if a member of the government or opposition was spied on in the same way? Heads would roll over this," he said.

"A member of the Australian Parliament has been spied on for doing nothing other than her job, in an effort to try and shut down any scrutiny of what is going on in our offshore detention network."

The Australian government pays Transfield Services to operate the Nauru centre. Wilson Security is engaged as a subcontractor.

Senator Di Natale said Wilson was a "lawless government contractor" that should not be responsible for the security of asylum seekers.

"This is a law unto itself, what is going on on Nauru, and it has to stop," he said.

"If they're prepared to go to these sorts of depths to spy on members of the Australian Parliament, God only knows what is happening to those innocent men, women and children who are locked up on in these camps."

He called on Mr Dutton to apologise for ridiculing the senator.

Comment has been sought from AFP and Mr Dutton.

Labor immigration spokesman Richard Marles reportedly told Sky News any surveillance of Saenator Hanson-Young would be "a disgrace" and Mr Dutton  should say if the government authorised the spying.