OTTAWA - The Harper government is leaving a probe into the security failings of Maxime Bernier in the hands of bureaucrats who could be implicated in their own inquiry, Liberals warned Friday.

Questions about Bernier's abrupt resignation as foreign affairs minister continued for a fourth straight day in the House of Commons, with the Tories maintaining that the only review of Bernier's misplaced NATO documents will be led by foreign affairs officials.

"In conducting their review, the Department of Foreign Affairs can of course draw on the other resources of government that they need, whatever agencies necessary, to assist them,'' Conservative House leader Peter Van Loan said.

But Bob Rae, the Liberal foreign affairs critic, said such a review flies in the face of a "basic principal of natural law.''

"Surely the minister understands a very simple distinction between an administrative review carried out by officials who may in fact be implicated in some of these questions, and an independent inquiry.''

Bernier tendered his resignation Monday just before his controversial ex-girlfriend, Julie Couillard, went to air with a damning interview.

Couillard -- whose past romantic links to three different men associated with the Hells Angels set off the controversy early in May -- revealed that Bernier had left classified briefing documents for a NATO summit at her house for more than month.

Couillard returned the documents, through her lawyer, only Sunday.

The Harper government maintains there's no ongoing security issue and has ignored calls for an RCMP investigation, insisting an internal probe is good enough.

Van Loan, Prime Minister Stephen Harper's utility infielder who's routinely assigned to smother opposition hits, did offer one sliver of new information Friday.

He strongly implied that Bernier's controversial former girlfriend was never issued one of the red- or green-jacketed diplomatic passports that ensure privileged diplomatic transit.

Only spouses or common-law partners of ministers qualify for a diplomatic passport, Van Loan repeated several times in the Commons.

"I am not going to comment on whether any individual had a passport, but I will comment to this limited extent on the minister's private life: the minister was not in a legally married or legally recognized common law spousal relationship when he was minister.

"I am sure the member can follow that logic.''

But both the Bloc Quebecois and Liberals continued to press for a declarative Yes or No to the question of Couillard's passport.

Outside the House, Liberal MP Denis Coderre said the Conservatives' implied assurances can't be taken at face value.

"Nobody buys what they're saying for the last three weeks,'' said Coderre.

Opposition MPs are convinced an official whitewash is in the works to mask the extent of government bumbling or duplicity.

The Tories counter that most of the Opposition questions relate to a prurient interest in Bernier's flamboyant former paramour.

"We do not intend to have a public inquiry into a personal relationship,'' Van Loan said Friday.

Rae said the Conservatives have become adept at deflecting questions on a range of subjects simply by attacking the character of the questioner.