OTTAWA — The Bloc Quebecois filed a police complaint over what it described as sabotage in one of four federal byelections Monday.

The Bloc says it contacted police after someone impersonated one of its members in a phone call Monday to voters in eastern Quebec. It says someone pretending to be Bloc MP Christiane Gagnon left bizarre, recorded messages urging people to vote for her colleague Nancy Gagnon.

Nancy Gagnon is hoping to hold the Riviere-du-Loup-area riding for the party, in a hotly contested race against the Conservatives.

The riding is considered a potential bellwether and victory would be considered a huge coup for the Tories.

The Bloc says someone pretending to be their Quebec City MP left halting, unprofessional-sounding phone messages urging people to vote for the Bloc - and it says the calls were designed to leave a negative impression of the party.

The MP filed a police complaint, party president Hugues Belzile signed an affidavit, and the party is also complaining to Elections Canada.

"What we want is an investigation to know who's behind this operation," Christiane Gagnon said in an interview.

Reported by The Canadian Press.