Ontario's premier and Opposition leader are sticking to their guns in a dispute that could lead to legal action.

Premier Kathleen Wynne's lawyers wrote a letter to Patrick Brown on Wednesday asking that he withdraw comments he made about her or face a defamation lawsuit.

In a statement released early this morning, the Progressive Conservative leader said he is ignoring the premier's request and her "baseless" warning about legal consequences.

When asked whether she would proceed with a lawsuit, Wynne -- who is in Washington, D.C., today -- said her letter "stands" and "speaks for itself."

She says her lawyers are discussing the next steps.

One of her lawyers, Jack Siegel, told a Toronto radio station that Brown's response is "disappointing."

"It would be rather nice, I would think, if Mr. Brown would simply acknowledge...it was a slip of the tongue and we could be done with this," he told Newstalk1010.

At issue are comments Brown made about the premier's role in a Liberal bribery trial.

The letter sent to Brown said he told reporters Tuesday that Wynne was standing trial, when in fact she is not on trial or even under investigation, but is offering voluntary testimony.

It was made public moments before Wynne took the witness stand at the trial in Sudbury, Ont., where her former deputy chief of staff and a local Liberal are facing bribery charges under the Election Act.

Brown's office had previously suggested he misspoke while talking to reporters and pointed out that he immediately tried to clarify his comments. But Brown appeared to stand by his words.

"Yesterday was a sad day for Ontario," he said.

"No one, whatever their political view, wants to see the premier of our province debased and humiliated. Regrettably Kathleen Wynne compounded this sorry spectacle with baseless legal threats against me; threats that will be ignored," Brown said.

"We as a province need to put this ugly chapter behind us and move on."

This is the second time in a week that the Liberal government has threatened legal action over remarks made by a Progressive Conservative member of the provincial legislature about the Sudbury trial.

Last week, Bill Walker told a local radio station Wynne was under investigation and facing charges in connection with the bribery trial. Days later, he issued a statement apologizing for the remarks.

Wynne previously sued former Conservative leader Tim Hudak and another Tory member of provincial parliament after the pair said she oversaw -- and possibly ordered -- the destruction of documents related to two cancelled gas plants.

That lawsuit was resolved in 2015, though it is not known whether it was settled or withdrawn.