TORONTO - The campaign buses have barely rolled out for the June 12 election and already there's a flurry of open letters, accusations and even legal claims in a $2-million libel suit.

The Progressive Conservatives are denying they did anything wrong when they suggested that Premier Kathleen Wynne "oversaw and possibly ordered the criminal destruction of documents" related to the $1.1-billion cancellation of two gas plants.

In a statement of defence in response to a lawsuit launched by Liberals last month, the Tories say they had a "legal, social and/or moral duty" to make the statements the Liberals claim were defamatory.

The Tories are claiming qualified privilege, saying the public had "a corresponding interest" in hearing that information.

They say they were diligent in trying to verify the allegation and that it was an urgent matter of public importance.

Meanwhile, NDP Leader Andrea Horwath has sent an open letter to her rivals challenging them to participate in five debates, with one focused on jobs and the economy.