A former employee of the security firm at the Nauru asylum seeker detention centre says security guards spied on Greens senator Sarah Hanson-Young during her visit in 2013.

The unnamed whistleblower said security staff followed her around the island and set up an observation post to watch her hotel room.

In a submission to the Senate committee examining allegations of misconduct at the centre, the person said Wilson Security ordered the spying, with the team briefed by a supervisor from the Emergency Response Team.

"This briefing included her room number, vehicle registration and even using code name Raven over the radio to make reference to her," the submission says.

The Senate inquiry was launched in March and follows an independent review which uncovered cases of abuse of women and children at the Nauru detention centre, including guards trading drugs for sexual favours.

John Rogers, Wilson Security's executive general manager for the Southern Pacific, said the company strongly rejected the claim that it organised a team to spy on Senator Hanson-Young.

But he said the company was aware of individuals who attended the hotel at the same time as Senator Hanson-Young.

"We understand that their primary motivation was the security of the Senator," he said in a response to the whistleblower allegations.

Mr Rogers said that was not authorised by Wilson Security and was not part of their work in providing security at the centre.

"The matter was immediately investigated by Wilson Security and the individuals involved were subject to disciplinary actions for acting beyond their brief," he said.

Senator Hanson-Young said she would be referring this to the privileges committee.

She said this was a company contracted by the Australian Government, under scrutiny for its poor management of detention centres and now spying on a Senator of the Australian Parliament.

"It is only appropriate that a full explanation of what occurred is given. What information was gathered and kept, who has access to the information and, importantly, who on Nauru and the government knew," she said in a statement.

Senator Hanson-Young said it was simply unacceptable that neither the contractor or the Immigration Department have bothered to inform her that her privacy and parliamentary privilege had been breached.

"Some very serious questions need to be answered," she said.