John Gomery says Premier Danny Williams should leave Newfoundland and Labrador's breast cancer inquiry alone. (CBC)

Newfoundland and Labrador Premier Danny Williams was wrong to critique the tone and speed of the judicial inquiry investigating flawed breast cancer testing, John Gomery says.

"It's quite inappropriate to criticize an inquiry which is, after all, doing what it was asked to do, which is to get at the truth," Gomery, who oversaw the commission of inquiry into the federal sponsorship scandal, told CBC News Tuesday.

"Sometimes the truth is a little bit embarrassing, and sometimes the truth hurts. It shouldn't be criticized for doing what it is mandated to do."

Williams sparked an uproar Thursday night when he said the Cameron inquiry was using "inquisitorial methods" and had an overly aggressive tone. On Monday, a government lawyer applied to Justice Margaret Cameron to reconsider how inquiry counsel do their work.

As well, Justice Minister Jerome Kennedy has publicly criticized the cost of the inquiry — he said that $750,000 has been billed so far by lawyers working at the inquiry — and has said no decision has been made on Cameron's request to extend the inquiry from its July 30 deadline to the end of next February.

Danny Williams has used the words 'witch hunt' to describe how Cameron inquiry counsel have operated. (CBC)

Gomery, a now-retired justice who was appointed in 2004 to investigate the so-called Liberal sponsorship scandal, said inquiries should be left alone from political involvement.

"The inquiry is required to act independently. It isn't supposed to act in accordance with what he wants it to do," Gomery said.

"As long as it performs its function, that was assigned to it, it should be immune from any kind of political pressure or comment like that."

Gomery also said it was inappropriate for Williams to have used the phrase "inquisitorial methods." Williams told the legislature Monday he was inspired to do so because a physician at Thursday's meeting cited the Spanish Inquisition to describe the Cameron inquiry.

"The trouble with the term 'inquisitorial' is that it brings up images in our minds of the Spanish Inquisition and Torquemada torturing people and things like that, which of course is far, far, far from what is taking place," Gomery said.

Aggressive questioning OK, Gomery says

Gomery also challenged Williams's and Kennedy's view that inquiry counsel should not be aggressive with witnesses.

"Sometimes in order to get at the truth when there are witnesses who are not particularly co-operative or who are evasive in their answers, it is the task of the inquiry and its staff and its lawyers, and the commissioner herself, to press these people and to make sure that what they say under oath is accurate and is true, and to uncover people who would prefer that certain facts be covered up," he said.

"An inquisitorial approach isn't improper at all …The cross-examination of a witness is an essential part of the examination of the witness."

Williams said again Monday that he made the comments after meeting with physicians Thursday. Williams said he believed that physicians will move away from the province if they face aggressive questioning at the inquiry.

Gomery said the government should not limit Cameron with a deadline less than the seven-month extension that she is thinking.

Cameron begin hearing evidence in March on what went wrong at an Eastern Health lab with hundreds of hormone receptor tests, which are used to guide a breast cancer patient's course of treatment.

The inquiry has spent much of its time so far focusing on how Eastern Health and government officials responded to the problems when they were identified in 2005.