Two Montreal police officers have been suspended without pay and are facing criminal charges.

Police chief Philippe Pichet announced that a total of four officers were arrested on Thursday morning as the result of an internal investigation.

Two men, Faycal Djelidi and David Chartrand, were immediately suspended without pay, and are facing a dozen criminal charges.

Both have been charged with perjury and attempting to thwart justice, while Djelidi is charged with soliciting sexual acts and abusing the public trust.

Pichet said that both officers worked in the multidisciplinary squad and the youth division of the Southwest borough police detachment.

He was shocked by the investigation into officers, especially since Chartrand and Djelidi have 11 and 16 years experience on the force.

"It's not easy to see that some of our officers are going beside the rules. We have to follow rules when we are police officers," said Pichet.

"It's not a good day for us as Montreal police officers."

The two officers will be released from custody after making promises to appear in court at a later date.

Pichet refused to identify the two other officers arrested Thursday, but said they were picked up as part of the same criminal investigation.

Those officers are being questioned about Chartrand and Djelidi's alleged actions.

The police chief said the internal investigation began in December 2015 because of problems in how informants were being handled, adding that the force's experience with prior cases involving confidential informants helped raise red flags.

In February 2012, retired police officer Ian Davidson killed himself after it was revealed he was investigated for allegedly trying to sell the names of police informants to organized crime groups. In 2014, former investigator Benoit Roberge was sentenced to eight years in prison for selling police information to the Hell's Angels.

Pichet said he was not at liberty to say more because several of the allegations involve several cases that are still underway but insisted no lives were endangered by their actions, nor was any police work jeopardized.