Conservative leadership contender Lisa Raitt is calling on the party to expel any candidate who has broken the party's rules and levy "significant" fines on their campaigns.

The call comes amid a flurry of allegations of membership fraud and vote buying and a series of barbs traded between the Maxime Bernier and Kevin O'Leary camps as the race to replace Stephen Harper becomes increasingly contentious.

"Cheaters and rule breakers who do this discourage the involvement of both our long standing and new party members. It makes a mockery of their commitments and corrupts the process," Raitt said in a statement Monday. "I am deeply concerned about a leadership election process that has now been called into question."

Late last week, O'Leary called for a review of the party's membership list after he said "backroom organizers" were using prepaid credit cards to sign up "fake members." After a speedy investigation, the party struck 1,351 memberships from its voting list after the party found they had been purchased inappropriately.

Now Bernier's team is branding O'Leary a hypocrite, claiming they have proof that one of O'Leary's Sikh-Canadian organizers was offering to pay the membership fees of six would-be party members in Brampton, Ont.

CBC News has asked the Bernier campaign to produce the affidavit it shared with the Globe and Mail, but was rebuffed.

Raitt said that since the allegations first surfaced, "all people want to discuss is this very disturbing story. We cannot let our legitimate party members be impacted by this type of behavior.

"I am calling for the expulsion of any candidate found to have broken the leadership rules and a significant fine for any campaign found to have authorized this type of activity."

She didn't name the candidate she thought had engaged in this type of activity.

The former Harper cabinet minister said the party should ensure every new membership is validated by a third party audit.

Ari Lasken, O'Leary's spokesperson, said everything is above board.

"Mr. Chatha has not submitted any lists or memberships in bulk to the O'Leary campaign, and has only signed up his family," he said, referring to the name of the of the Conservative Brampton-East riding association president who is alleged to have offered to pay for memberships.

"The O'Leary campaign will continue to operate with transparency and by the rules," Lasken said. "Mr. O'Leary continues to call on the party for a full audit of the entire list when it is finalized at the end of the month."

Cory Hann, a spokesperson for the Conservatives, said the party regularly reviews memberships and will ensure all rules have been followed.

Party memberships must be purchased by 5 p.m. on March 28 in order to cast a ballot in the leadership race, and all voters submitting their ballots by mail are required to send a photocopy of their photo ID.

Conservatives will vote for a new party leader on May 27.