WASHINGTON - Canadian Prime Minister Stephen Harper said Monday that Foreign Minister Maxime Bernier has resigned from the cabinet for leaving classified document in an unsecured location. Harper made the announcement at a news conference in Ottawa on Monday afternoon that he has accepted the resignation of Bernier, who has been under fire recently for his former girl friend's links with an organised crime group, according to media reports. Bernier quit after realising that he had left "classified government documents at a private residence" earlier this year, Harper told reporters in Ottawa. "It's only this error. It's a very serious error for any minister," Harper said. "The minister immediately recognised the gravity of that error." "The security breach that occurred was my fault and my fault alone and I take full responsibility for my actions," Bernier wrote in his resignation letter. Canada's Opposition parties Monday reiterated calls for Bernier's resignation because of alleged missteps, such the minister's pledge to send a cargo plane to Myanmar that the military didn't have ready, and interfering in Afghanistan government affairs by suggesting an official there be replaced. Bernier has also been questioned by Opposition members of Parliament over media reports that his former girlfriend was previously involved with men connected to motorcycle gangs in Quebec.  His resignation was unrelated to that relationship, Harper said. "This is about one thing, and that is a failure to uphold expected standards on government documents," Harper said. "I don't think it matters who a minister is dating." David Emerson, Canada's trade minister, will assume Bernier's duties on an interim basis, Harper said.