Tensions flared in cities across Canada on Saturday as supporters and opponents of a Parliamentary motion condemning Islamophobia clashed during duelling protests.

In Montreal, there was a heavy police presence outside city hall keeping the two sides apart as a demonstration by critics of the motion was met by an equally large counter-protest.

On one side, some protesters carried signs calling for free speech and waved the flags of right wing groups that have sprung up in Quebec recently, while their opponents hurled insults and the occasional smoke bomb from behind a police line.

At one point, the counter-protesters' chants of "immigrants welcome" and "everyone hates fascists!" were countered from the other side by a man who called out "suppressing free speech is fascist!"

The two groups, which each appeared to be between 100 and 200 people, later held separate marches through the streets of Montreal.

Rheal Fontaine, who came waving a huge Quebec flag, said he was there to peacefully oppose the motion and stand up for freedom of speech.

"There's no more democracy in Quebec," he said. "What (Prime Minister Justin) Trudeau and (Quebec Premier Philippe) Couillard are doing is turning their backs on the Quebec people."

Many of those protesting the motion, including those from groups associated with the far-right, denied the other side's claims that they were racist or anti-immigrant.

But at the counter-protest, a university student who gave her name as Lauren was clearly unconvinced.

"These people are feeling threatened that their positions as white people in positions of power are being threatened," said Lauren, who said she was there in support of students who felt threatened in the wake of an alleged bomb threat targeting Muslims that was sent to Concordia University this week.

Despite police efforts to keep the two sides apart, some isolated scuffles occurred as tempers flared, and members of the counter-protest eventually set fire to a pile of flags and signs that the other side had left behind.

Police said there were no arrests or injuries.

An Ontario Liberal backbencher, Iqra Khalid, brought forward the motion in Parliament last year, and since then she has received numerous racist and sexually derogatory emails that were laced with expletives.

Heritage Minister Melanie Joly, who prominently backed the motion, also found herself on the receiving end of similar kinds of messages.

The Opposition tried to pass an amendment last month removing the word "Islamophobia'' from the motion, saying it singles out one religious group over others.

But the Liberals used their majority to block the effort.

Protests against the motion were expected to take place in several dozen cities.

In Calgary, a group of about 15 people reportedly gathered outside city hall to protest the parliamentary motion but were outnumbered by dozens of counter-protesters.

Demonstrators on both sides shouted at each other in Regina. Police were present but the event remained peaceful.

In Toronto, videos posted on social media showed protesters against the motion shouting "freedom!" and waving Canadian flags.

As in other cities, this demonstration was met by counter-protests, but there were no reports of any serious scuffles.

(CJME, CFFR, The Canadian Press)

--With files from Rob Drinkwater in Edmonton