The Liberals allege Foreign Affairs Minister Peter MacKay referred to ex-girlfriend and Liberal MP Belinda Stronach as a dog during an exchange Thursday in the House of Commons —a charge he later denied.

During the debateabout the Tories' clean air plan, MP Mark Holland said a fellow Liberal jokingly asked MacKay about the impact of pollution on humans and animals: "What about your dog?"

Holland alleges MacKay motioned in response toward Stronach's vacant seat and replied: "You already have her."

Hollandlodged a complaint with the Commons Speaker and has demanded MacKay apologize.

"It's completely unacceptable to call a woman a dog and to point over to her is completely disgusting," Holland, who represents theOntario riding of Ajax-Pickering, said after the session.

"And he owes Belinda an apology, he owes the House an apology, he owes women an apology."

Stronach was meeting with child-poverty groups in Montreal on Thursday, but issued a statement later in the day.

"I am really disappointed that Peter MacKay would say something like that," it read.

Stronach,a former Conservative leadership contender,had a high-profile breakup with MacKay when she crossed the floor to join the Liberals in May 2005.

The couple had been dating for months and MacKay retreated to his father's farm in Lorne, N.S., giving several emotional interviews and declaring his heart was "a little banged up."

While at a Tory fundraiser in Halifax on Thursday night, MacKay denied making any derogatory remarks about Stronach and said the Liberals were engaging in partisan politics.

"I made no dog comment," said MacKay.

"It's a distraction away from their own inadequacies," he added.

The twice-divorced Stronach has attracted attention in recent weeks after itwas alleged that she had an affair with former Toronto Maple Leaf Tie Domi. The allegation was made by the hockey player's ex-wife, Leanne.

Stronach released a statement denying responsibility for the dissolution of the marriage.

MacKay, meanwhile, has prompted media speculation about his relationship with U.S. Secretary of State Condoleezza Rice, particularlyafter her visit to Nova Scotia in September. Rice's spokesperson later denied there was any romantic relationship.