Ottawa police are calling for backup to help deal with an invasion of hundreds of motorcycle gang members this weekend as the Hells Angels gather in Carlsbad Springs to celebrate 15 years in Ontario.

Insp. Michel Marin said Ottawa police are expecting at least 500 bikers to descend on the east Ottawa community between Friday and Sunday, and are counting on reinforcements from Gatineau police, Ontario Provincial Police and Sûreté du Québec.

"This is probably the largest gathering of motorcycle [gang] members ... in the history of Canada," Marin said.

Police said they don't expect to make major arrests, but they are prepared to keep close tabs on the bikers

"They themselves have told their members they expect them to be on their best behaviour," Marin said. "Generally, these gatherings tend to be rather large, but in terms of numbers of arrests, based on previous plans, we don't see police services arresting a lot of members of the outlaw motorcycle gangs."

Gang gathers strength as members freed

OPP Biker Enforcement Unit Det.-Staff Sgt. Len Isnor said the gang's strength has increased in recent years because many members have completed prison terms and been released.

"They're starting to come out of jail," Isnor said. "There's never been a time ... over the past six, seven years that there's been more back on the streets."

Det.-Staff Sgt. Len Isnor is operations coordinator with the Biker Enforcement Unit of the Ontario Provincial Police.

2016 marks the 15th anniversary of the 11 Hells Angels chapters in Ontario. This weekend's national gathering marking the milestone, called a "Canada Run," will include members from Quebec and western Canada. Attendance is mandatory for members of the gang.

'Red Devils' establish local foothold

In March, Isnor spoke to CBC News about a Hells Angels "farm team" called the Red Devils that was establishing itself in Ottawa and Gatineau. He said this weekend's national gathering will demonstrate the "power of the patch" to possible new recruits.

"Having the numbers here and riding through the community is going to have an impact," Isnor said.

As recently as June 29, OPP raided the Carlsbad Springs Hells Angels compound to execute a search warrant in connection with a larger SQ operation against motorcycle gangs in the Eastern Townships.

The Red Devils gang, which operates as a 'farm team' of the Hells Angels, has three branches in the Ottawa-Gatineau region, according to police. (CBC ) While the larger SQ operation, called Project Muraille, seized drugs, money and weapons, investigators wouldn't specify what — if anything — was found at the Carlsbad Springs location, and no charges were laid there.

In April, Phil Boudreault, a Hells Angels leader in Ontario, was hospitalized in Ottawa for about three months after he was shot multiple times on a Quebec highway.

While police wouldn't comment on which members they're on the lookout for this weekend, they say they are prepared to respond to anything while maintaining sufficient policing throughout the rest of the city.

On Wednesday Quebec Provincial Police announced the arrest of André Sauvageau in Montreal. The 60-year-old is described as an influential member of the Hells Angels. Police have charged him with gangsterism, narcotics trafficking and hiring someone to commit a criminal offence.