TORONTO -- Patrick Brown refused Monday to shed light on a controversy that saw voters in a Toronto riding receive a letter bearing his signature promising that the Progressive Conservative leader would "scrap" the Liberal sex-ed curriculum.

The letter -- which the Liberals say was distributed in several languages -- was sent to voters in Scarborough-Rouge River riding ahead of the Sept. 1 byelection that the Progressive Conservatives ultimately won.

Days after the letter became public Brown disavowed it, saying he supports the curriculum.

Brown said he only found out about the letter after it was sent out and suggested it was the work of the local campaign that "went too far."

But The Canadian Press obtained an email that Brown's chief of staff, Nicolas Pappalardo, sent to an independent candidate opposed to the new sex-ed curriculum the day before Brown said he learned of the letter.

"As a courtesy, please find attached an open letter to parents from the Leader of the PC Party of Ontario," Pappalardo wrote in the email. "It will be distributed in the riding this weekend."

Queenie Yu, the independent candidate who received Pappalardo's email, said if she received it early on a Thursday afternoon, "it would have been unlikely that the leader himself did not know about it until mid-day on Friday."

Party president Rick Dykstra told television station CP24 the night of the byelection that he knew about the letter "when it was first put out."

Brown refused for more than a week after Pappalardo's email emerged to take questions on how his top staffer came to distribute a letter that espoused the exact opposite of what Brown says are his true views on sex ed.

In a news conference Monday, Brown repeated that "a mistake was made," but would not say how or by who.

"I apologized for it and assumed responsibility," he said. "Ultimately the buck stops with me. I took responsibility and owned it."

But he maintained that the pledge in the letter to "scrap" sex ed was news to him.

"A mistake was made and it's a mistake that I hope never happens again," he said.

Brown said he will be looking at his office's organization, but declined to comment further on what he called the internal operations of his office or the party.

The sex-ed controversy dominated the last week of the byelection campaign in a riding where the curriculum has not been well received. A promise to scrap it would have been popular, Brown has acknowledged.

The curriculum was updated last year for the first time since 1998, but complaints from some parents ranged from not being consulted enough to the lessons being age inappropriate to anger over mentions of same-sex relationships, gender identities and masturbation.