The Senate clerk has acknowledged concerns the Government's decision to release personal information to a journalist could have a "chilling" impact on sources.

Key points: Senate clerk recognises concerns about DHS information leaks

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The Department of Human Services (DHS) has stood by a decision to release a Centrelink client's personal information to a journalist to counter her claims in the media.

But the Federal Opposition has referred Human Services Minister Alan Tudge to the Australian Federal Police to determine whether any rules were broken.

An inquiry will investigate Centrelink's controversial debt recovery program next week, and the Greens want assurances that testimonies will be protected by parliamentary privilege.

"I sought this advice because I am concerned about potential witnesses not feeling comfortable about giving evidence to the inquiry, or making submissions, because of the Government's recent behaviour," Greens senator Rachel Siewert said.

"Given Government's release of personal information on Centrelink recipients who speak out about the Centrelink debt recovery system, it is important that everyone including the Government is clear about protection of witnesses.

"I had concerns that people may be deterred from putting in submissions and speaking at the inquiry hearings."

Acting Senate clerk Richard Pye told the senator that any attempt to interfere with or intimidate a witness would be considered as contempt.

"If people are concerned that adverse consequences will flow from their giving evidence, this may have a chilling effect on sources of information for the committee's inquiry and undermine its work," he said.

"The law of parliamentary privilege protects witnesses against intimidation and against the imposition of penalties connected to their giving evidence."

The Senate may deal with any such conduct as contempt.

DHS insists the release of personal information was legal, appropriate and proportionate but some legal academics believe the relevant legislation should be tested.

Mr Tudge and his department claimed the disclosure was legal according to section 202 of the Social Security Act 1999 and section 162 of the A New Tax System Family Administration Act 1999.

In a statement, Mr Tudge said the Government took privacy "very seriously" and said information was released to the journalist after approval from the department's chief legal counsel.

DHS has told the ABC it will continue to release public information should it feel the need to correct the record.

Centrelink's debt recovery program has faced criticism since December.

Public servants revealed on Thursday that more than 6,000 people had been contacted by debt collectors before they were told they may owe money.