Government ministers are breaking ranks on a controversial probe into the leak of a report on spying, with Justice Minister Judith Collins saying it was conducted with a "contemptuous attitude".

Former IRD commissioner David Henry, who headed an inquiry into who leaked a report into the activities of the Government Communications Security Bureau to Dominion Post journalist Andrea Vance, faced a grilling from the privileges committee yesterday over its methods.

The inquiry has already come under fire for accessing information, including Vance's movements within Parliament, and was yesterday attacked by several ministers.

"I felt it was a chilling experience to realise that ministers and staff emails and their right to privacy was treated with what I would say was, frankly, a contemptuous attitude," Ms Collins told Mr Henry, referring to the way the inquiry had sought information about MPs.

"Did it to occur to you, Mr Henry, with all your vast experience in government, that this actually might be an issue where you needed to get clarification on before requesting the information?"

Mr Henry conceded he had never had any contact with Speaker David Carter on the inquiry, or Parliamentary Service head Geoff Thorn, who quit after it was revealed his organisation handed over Vance's phone records to the Henry inquiry.

But Mr Henry maintained he was simply doing his job.

"I simply asked for what was necessary . . . I left it to the people [involved] to determine what could be supplied."

His report made no definitive claim about who leaked the report, but pointedly said UnitedFuture leader Peter Dunne had refused to co-operate fully with the inquiry, stifling the investigation.

Mr Dunne resigned as a minister in early June after facing an ultimatum from Prime Minister John Key to hand over emails between him and Vance, or fall on his sword.

Mr Key has repeatedly backed Mr Henry, as well as his own chief of staff Wayne Eagleson and the chief executive of the Department of Prime Minister and Cabinet, Andrew Kibblewhite, for their roles in the inquiry.

Yesterday he dismissed concerns over the inquiry, saying no minister had complained about the terms of reference which made it clear he expected necessary information to be sought, and for ministers to co-operate.

It was "the most basic level of intrusion" to look at metadata to determine whether individuals were of interest.

"If you can't meet that level, you wouldn't make it as a minister," Mr Key told reporters.

Gerry Brownlee said it appeared Mr Dunne had been denied natural justice, by relying on his privilege as an MP but facing a report which criticised him.

ACT MP John Banks said he was yet to get to the bottom of whether Mr Thorn was the "appropriate scapegoat" of the conduct of the inquiry.

Mr Thorn said the lack of contact about the status of the report led to later problems. "There was never any communication to me about the legal status of the inquiry, its terms of reference or the basis on which information was being requested. In hindsight I believe this was a contributing factor to the errors that subsequently happened," he said.

However, he defended the decision to hand over Vance's swipe card records, claiming the freedom journalists had to move within Parliament was a security issue.