OTTAWA - Natural Resources Minister Lisa Raitt will not lose her job over a security breach involving sensitive government documents.

But one of her staff members has resigned after CTV revealed that a binder of documents on Atomic Energy of Canada Ltd. was left at its Ottawa bureau for nearly a week.

"It's our assessment that while this was a serious breach, it was not a breach by the minister herself," Kory Teneycke, a spokesman for Prime Minister Stephen Harper, said Wednesday.

He said Raitt offered her resignation, but Harper refused.

The resignation of the staff member, who was not named, was accepted.

Earlier Wednesday, former cabinet minister Maxime Bernier -- who resigned over a similar gaffe -- said it should be up to Raitt to decide whether to step down.

"I think she has good judgment. She must use her judgment like I did in my circumstance," he said.

"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.

At the time, 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."

CTV said the AECL 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."

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

A spokeswoman for Raitt declined comment.

Liberal MP David McGuinty wondered how the missing documents could go unnoticed for six days and drew comparisons to Bernier.

"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."