TORONTO - There are fresh allegations of dirty tricks in the Progressive Conservative leadership race, and this time, the cops are getting involved.

Provincial police are investigating a letter allegedly sent to a "handful" of Tories that claims the RCMP is conducting a criminal probe into allegations of voter fraud in the race, party president Ken Zeise said Thursday.

The letter, which was sent just a few days before voting began last Sunday, seems to have been designed to intimidate voters, he said.

"We don't want to blow things out of proportion," Zeise said.

"But if one member of our party gets a misleading document that suggests they may not be able to participate in our process, we take that seriously. We want to go after whoever is responsible."

Zeise said he has no idea who sent the letter, but isn't ruling out someone from outside the party.

"I thought it was so unprofessional looking, it just didn't look real," he said. "So I don't know what his point was."

The party will conduct its own probe, he added.

The Tories started investigating the matter after two leadership campaigns complained that members had received the mailing.

Leadership contender Frank Klees, who made the complaint to the party brass, said the "disturbing" letter was mailed to visible-minority Tories.

"It's disturbing that this kind of campaigning has gone on. I think it shows desperation on the part of someone," he said.

"Anything at all that's designed to suppress the expression of new Canadians, not only as part of our party but as part of the political process, is unconscionable."

Party members don't have to be Canadian citizens, but they must be Ontario residents, Zeise said.

Things took a nasty turn in the leadership race last week when officials for another candidate, Tim Hudak, complained to the party about what they claimed were dirty tricks being pulled by Klees supporters.

The Hudak camp accused the Klees campaign of using a pollster to ask "a battery of negative questions designed to smear" Hudak, whose campaign is backed by former premier Mike Harris.

Klees denied his campaign had conducted any so-called push polling, and the party dismissed the complaint last Saturday, saying it was without merit.

Thursday was the last day for party members to vote for a new leader, who will be named Saturday at a convention in Markham, north of Toronto.

Insp. Dave Ross confirmed Thursday that provincial police are investigating, but declined to discuss details of the case.