A member of the Ontario legislature is apologizing to Premier Kathleen Wynne for comments made in a radio interview after the premier's lawyers warned he could face a defamation lawsuit.

Lawyers representing Wynne sent a letter Wednesday to MPP Bill Walker asking that he publicly retract and apologize on the air for statements made to Toronto radio station AM640 on Monday.

The letter alleged Walker told the radio station Wynne was under investigation and facing charges in connection with an upcoming Election Act bribery trial for two Liberal party members, when in fact the premier is slated to testify in the trial.

It said his statements "could be the subject of a defamation action" and warned against making any further comments along those lines.

In a statement released Wednesday evening, Walker said he made a mistake while discussing Wynne's plan to testify at the upcoming trial.

MPP Bill Walker speaking at Queen's Park in March. (Facebook)

Pat Sorbara, the premier's former deputy chief of staff, faces two bribery charges under the Election Act, and Gerry Lougheed, a Liberal fundraiser, faces one charge.

"I misspoke by implying that the premier is under investigation and facing charges. The premier is not, in fact, under investigation or facing charges," he said.

"I regret the error and apologize for it without reservation."

Wynne's lawyers did not immediately respond to a request for comment.

In their letter, they said Walker's radio statements "appear to have been made with the intention to harm the reputation of Ms. Wynne," who they said has co-operated with investigators in the case.

"Despite the inaccuracy of your statements, your status as an MPP increases the likelihood that these falsehoods will be repeated by others, increasing the potential harm to the premier's reputation," the letter read.

"Accordingly, you will be held accountable for any damages arising from your defamatory statements and their repetition by others."

Wynne previously sued former Conservative leader Tim Hudak and another Tory MPP 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That lawsuit was resolved in 2015, though it is not known whether it was settled or withdrawn.