Canada's criminal laws are tough enough to tackle terrorism, says Liz Rowley, leader of the Communist Party of Canada.

She's worried the Conservatives' new anti-terrorism legislation, Bill C-51, would weaken democratic, labour and civil rights while making it easier for a government to abuse its power.

"The government has no business spying or doing the kinds of things they seem to be giving themselves the authority to do," Rowley said in an interview Thursday.

Bill C-51 is working its way through Parliament. The Liberal Party is supporting the bill while the NDP opposes it.

It would make it easier for law enforcement agencies to exchange information, allow spy agency CSIS to intervene in terrorism plots instead of just gather information on them, and make it easier for police to control activities of people suspected of terrorism activities with a peace bond.

Rowley warned it will allow the government to classify environmental protesters and other activists as terrorists. She's also concerned it gives CSIS too much power to peer into the lives of ordinary Canadians.

"This is a war on Canadians - not on terrorists. On Canadians who might be critical of this government or other governments," Rowley said.

The answer is to disband CSIS altogether and leave anti-terrorism investigations to police.

"We don't think we need a political police. We think the criminal laws are strong enough to deal with any criminal situation."

The Communist Party has seen the heavy hand of government excess. Illegal wiretapping of its Toronto office was documented in the MacDonald Royal Commission in the early 1980s.

Twitter: @Corey_Larocque