Ontario's integrity commissioner says he is launching an investigation into the conduct of ousted Progressive Conservative leader Patrick Brown.

J. David Wake says his office has started probing a complaint against Brown made by Tory legislator Randy Hillier.

Last week, Hillier asked Wake to look into Brown's financial disclosures and travel, alleging the former leader contravened legislation that governs Ontario politicians' conduct.

Brown has denied Hillier's allegations, calling them "entirely fictional".

Wake gives no timeline for the completion of his investigation but says his findings will be made public.

Brown resigned as Tory leader in late January after CTV News reported allegations of sexual misconduct against the 39-year-politician that he has vehemently denied. He has since launched a bid to reclaim his old job.