MONTREAL—With the proof caught on video, Quebec provincial police were forced to admit Thursday that three undercover agents were playing the part of protesters at this week’s international summit in Montebello, Que.

But the Quebec police force denied they were attempting to provoke protesters into violence. Rather, they said the three were planted in the crowd to locate any protesters who were not peacefully demonstrating.

Police said the trio’s cover was blown when they refused to toss any objects.

“At no time did the Quebec provincial police officers act as agents provocateurs or commit criminal acts. Also, it is not part of the policy of the police force nor is it part of its strategy to act in this manner. At all times, the officers responded to their mandate to maintain law and order,” the QPP said in a news release on Thursday night.

The police said after viewing a video clip from YouTube.com and video shot by police officers, they were able to confirm the three were Quebec provincial police officers.

Earlier, both the QPP and the RCMP had denied altogether any of their officers were involved.

The Quebec provincial police declined to comment further, a spokeswoman in Montreal said. And while Quebec Justice Minister Jacques Dupuis was made aware of the news, a spokesman from his office said he will not comment on the matter either.

Public Safety Minister Stockwell Day rejected opposition calls Thursday for an inquiry into agents role in trying to provoke protesters into violence at this week’s North American leaders summit in Montebello, Que.

“I’ve made the inquiries and there was no RCMP that were involved as far as those three individuals go,” Day told reporters after making a crime-prevention announcement in Winnipeg.

“If people have concerns ... there is a complaints process for the RCMP. There is also one for the Surete du Quebec. This incident happened in Quebec, so I imagine people could also file under that complaints process.”

Day’s words did little to appease Dave Coles, the union leader who confronted the three men on the protest line and accused them of being cops.

“We’re going to talk to our legal counsel and we’ll decide (Friday) what our next action is going to be,” said Coles, president of the Communications Energy and Paperworkers Union of Canada.

The Liberals called for a police probe into the issue, while the NDP called on Day to launch a public inquiry. The NDP said the public should be worried about the possibility police officers were used to try to turn a peaceful protest into a violent one.

“If they are police officers, and if they are stepping forward with a mandate to disrupt in any way, that’s a cause for concern,” said New Democrat MP Peter Julian.

The three officers, sporting bandannas, showed up on the front lines of a peaceful protest at the Security and Prosperity Partnership summit earlier this week.

One carried a large rock, and protesters allege the officers were trying to incite a riot so that police could move on the crowd.

The event was captured on video and shows one of the mystery men talking to police officers before being brought to the ground, handcuffed and quietly led away along with his friends.

The men were never charged, and photos show them wearing combat boots with identical markings to the ones worn by police at the scene.

“It’s just too coincidental that these guys attack a (police) line with a boulder and they’re not charged,” Coles said.

“The other four protesters who were arrested (over the weekend) were all charged.”

Quebec Provincial Police and the RCMP have both said they do not use agents to provoke violence.

RCMP spokesman Cpl. Luc Bessette said this week he could not discuss details of security measures for major events such as the summit because it could compromise future operations.