OTTAWA - A former cabinet minister who resigned after losing sensitive documents says it's up to Natural Resources Minister Lisa Raitt to decide whether to step down for a similar gaffe.

"I think she has good judgement. She must use her judgment like I did in my circumstance," Maxime Bernier said Wednesday.

"I did what I had to do at my time. I assumed my own responsibility. She's going to do what she thinks is good for the country and for her."

Bernier resigned as foreign affairs minister last year after it was revealed that he left sensitive government documents at his ex-girlfriend's home.

A national news agency reported that Raitt or one of her staff left behind a binder of documents on Atomic Energy of Canada Ltd. at the network's Ottawa bureau nearly a week ago.

The report said the documents list millions of dollars in funding for the Crown-owned corporation that have not been made public, including $72 million to "maintain the option of isotope production."

The documents also included a handwritten note that lists total funding for AECL since 2006 at $1.7 billion, and then a talking-point memo describing the spending as "cleaning up a Liberal mess."

The network said a federal government employee picked up the documents Wednesday morning after a story aired the night before.

The Prime Minister's Office is now investigating how Raitt, or one of her aides, left behind the documents.

A spokesman for the prime minister, Kory Teneycke, said the government is still establishing what happened.

A spokeswoman for Raitt declined comment.

At least one cabinet colleague leapt to her defence.

"I think Lisa does a wonderful job. She's been a real addition to our caucus," Defence Minister Peter MacKay said.

"I think her performance, in my view, has been spectacular."

Last spring, Bernier left classified NATO briefing documents at the Montreal home of Julie Couillard for more than a month. At the time, Prime Minister Stephen Harper said it's up to cabinet ministers to protect sensitive documents.

"Ministers are always responsible for the protection of classified documents," Harper said in the House of Commons.

"The minister admitted that he failed to protect classified documents. That is why he offered his resignation and why I accepted it."

Liberal MP David McGuinty wondered if the same fate will befall Raitt.

"That (Bernier incident) was a different situation because, of course, the minister made a series of repeated, incompetent mistakes," McGuinty said.

"In this case, the question really is now: Will the prime minister live up to his own standard. ... He has applied that test. And the question now is whether he's going to be consistent."

A review of the Bernier incident recommended a range of measures to beef up ministerial security, including better training, stricter monitoring and improved measures for tracking briefing books.

It's not the first time Raitt's department has come under scrutiny for document security.

A 2006 audit by the Natural Resources Department on the security of cabinet documents found "key employees are still unaware of the proper handling and safeguarding of cabinet documents. This increases the risk of security incidents which could compromise sensitive information."