Gun-control advocates, police officers and suicide experts joined forces in Montreal on Tuesday to say that the Harper government is making a mistake by cancelling the long gun registry.

The group told a news conference that rifles and shotguns are often used to kill police officers and women and to commit suicide. The warning came just two days after the 20th anniversary of the Ecole Polytechnique massacre.

The groups were joined by Sylvie Haviernick, whose sister Maud was among Marc Lepine's victims on Dec, 6, 1989.

Haviernick says the registry can save lives, and she added it's shameful that any politician would vote to abolish it.

"It's sad to see that (they're) exchanging a vote for a life -- that's really, really bad."

The Coalition for Gun Control and groups representing police officers are gearing up for a major push to try and save the registry. Last month the House of Commons approved in principle a private-member's bill to scrap it.

Explanation

The registry was created under the previous Liberal administration after intense lobbying by advocates spurred into action by the 1989 massacre.

The Conservatives say the registry is too expensive and does not curb gun violence but Yves Francoeur, president of the Montreal police union, told the news conference the Tories are wrong.

"As a police officer I was at Polytechnique on December 6th 1989," he said.

"Police across the country use the gun registry 11,000 times a day. We have used the registry to remove guns from dangerous people and to solve crimes. We need to know what guns an individual owns so they can be held accountable."

A recent poll indicated most Quebecers want to keep the registry, but a majority of people in the rest of Canada want it to be scrapped.