Lawyers for Ontario Premier Kathleen Wynne have issued notice of a libel suit against PC Leader Patrick Brown over comments he made suggesting she was on trial.

Brown was speaking to reporters at Queen's Park about the Sudbury byelection bribery scandal last month and said that Wynne may only provide answers "when she stands trial."

Within a few days, Wynne's lawyers called on him to apologize and retract the statement, but Brown declined.

"You have refused to retract or apologize for those defamatory statements, and have made further defamatory statements about Premier Wynne," said the letter to Brown from lawyer Jack Siegel.

"Accordingly, a legal action will now be commenced against you for defamation," said Siegel in the letter.

The letter is dated Thursday and was provided to the news media on Friday by Wynne's press secretary.

Brown, who was a lawyer before entering politics, made the original comments on Sept. 12, the day before Wynne testified in the bribery trial of two senior Liberals. He was responding to a question from CBC Queen's Park reporter Mike Crawley during a scrum at the Ontario Legislature.

Ontario Premier Kathleen Wynne was called by the Crown as a witness in the trial of bribery allegations during the 2015 Sudbury byelection. (Yvon Theriault/Radio-Canada/CBC)

"The fact that the police have been brought in just shows how serious it is," said Brown at the time.

"So I hope that the premier will give us answers. We're not getting them in the legislature, maybe when she stands trial. That in itself is astonishing, that we've got a sitting premier sitting in trial and answering questions about these allegations of bribery."

Provincial law required Wynne's lawyers to issue a libel notice within six weeks of the comments, making the deadline next Tuesday.

"The express meaning of these statements is that Premier Wynne was on trial for bribery, which was not the case," said the letter. "Your stubborn refusal to retract your defamatory statements has exposed you to an award of aggravated and punitive damages."

The lawyer warns Brown to preserve all relevant documents related to the accusations in the case, including emails and recordings.

Brown calls legal threat 'baseless'

In a statement Friday afternoon, Brown dismissed the libel notice as an attempt by the Wynne government to distract attention from bad news this week, such as a critical auditor general's report about its hydro rate cuts.

"The premier needs to apologize to Ontarians for years of waste, mismanagement and political corruption in this province," the statment read. Brown also said the "baseless legal threats against me ... will be ignored."

Sending a notice of libel is a step required by Ontario's Libel and Slander Act before actually filing a defamation suit.

Wynne testified last month in Sudbury at the bribery trial of her former deputy chief of staff Pat Sorbara and local Liberal organizer Gerry Lougheed Jr.

Lawyers for Sorbara and Lougheed have asked the judge to toss out the charges, arguing that the Crown has failed to prove its case. A ruling is expected on Tuesday.

In 2014, just before the last provincial election, Wynne sued then-PC leader Tim Hudak and MPP Lisa MacLeod over comments alleging that she had overseen "and possibly ordered" the criminal destruction of documents. The suit was dropped in 2015.