While he's concerned about ongoing protests along rail tracks in Quebec and Ontario, Public Safety Minister Bill Blair said this morning they don't constitute acts of terrorism, as some Conservative MPs are suggesting.

On Wednesday, protesters set tires on fire and tossed them onto the track near Belleville, Ont., as CN Rail trains — which often carry flammable chemicals and petrochemical products — rolled by.

During this morning's meeting of the House of Commons public safety and national security committee, Conservative MP Doug Shipley asked the minister whether the blockades are being examined as terrorist activity under the Criminal Code.

"No, they're not," responded Blair.

Shipley pushed back, asking why the blockades aren't considered acts of intimidation against the public. The MP for Barrie-Springwater-Oro-Medonte said he was asking the question on behalf of a constituent.

WATCH: Blair says blockades are not terrorism

Public Safety Minister Bill Blair tells the Commons national security committee that rail blockades do not constitute acts of terrorism, in response to a question from Conservative MP Doug Shipley. 1:49

"I agree definitely with proper civil demonstrations. I'm all for that. But when we're seeing certain things like I saw yesterday, with burning goods on rail lines across Canada, I thought that may have crossed a line," he said.

Blair said that, as minister, he has a responsibility to leave it to police to use their discretion in investigating potentially criminal acts.

"I would not leap to that determination but leave it to the police and to our prosecutors to determine whether or not any conduct meets a threshold of that level of criminality," he said, adding that what he saw near Tyendinaga Mohawk Territory outside Belleville yesterday was "terribly unsafe" and "deeply concerning."

A fire burns on CN Rail tracks in Tyendinaga, near Belleville, Ont., on Wednesday. (CBC)

In an online statement, Conservative MP and party leadership candidate Erin O'Toole said the protesters "crossed the line from illegal protest to terrorism.

"That's how it should be treated," he tweeted Thursday morning.

RCMP head says officers 'were very patient' with Wet'suwet'en protesters

The head of the RCMP was also at the committee meeting, where she was asked about the RCMP's role in the protests.

Earlier this month, the RCMP, which acts as the provincial force in B.C., enforced a court injunction against protesters preventing contractors from accessing the construction area for the Coastal GasLink project, which would carry natural gas from near Dawson Creek to a coastal LNG Canada export terminal in Kitimat.

"The discussions for us are always not if we're going to enforce an injunction, it's how we're going to enforce it and when we're going to enforce it, so we can get the most peaceful outcome," RCMP Commissioner Brenda Lucki told the committee Thursday morning.

"And that's exactly what happened. We were very patient. It took several days and we cleared the [Morice West Forest Service Road] road ... We have the discretion of a couple of things in an injunction, mostly about the timing and the intensity. So we can decide when and how we will enforce it even though the injunction is in place."

Lucki said dialogue continues between the B.C. RCMP and the hereditary chiefs.

"We have a specific policy that we have created specifically for Indigenous blockades," she said. "Of course, enforcement is the last option."

Lucki's Thursday morning appearance before the Commons national security committee happened before a proposed meeting between the Wet'suwet'en hereditary chiefs, the federal government and the British Columbia government following weeks of simmering tension.

Last week, the RCMP in British Columbia moved its officers out of an outpost on Wet'suwet'en territory to a nearby detachment in the town of Houston.

The hereditary chiefs of the Wet'suwet'en Nation have said they would not meet until the RCMP leave their traditional territory entirely and the pipeline company ceases work in the area.

Blair has said the people who live there have a right to be protected by police.

"I think there's a very important principle: There are thousands of Canadians that live in that area [that] are entitled to policing services," he said.

"They are entitled, as every Canadian is, to be served and protected by a police service, and that's what takes place in all parts of Canada, including in British Columbia."