Dozens of alleged motorcycle gang members were rounded up in raids across Ontario in the early morning hours Thursday, police said.

About 500 officers arrested alleged members of the Hells Angels, Vagabonds and other associated biker gang members during raids in the Windsor, Niagara and Toronto areas, said Ontario Provincial Police Const. Sally Stewart.

The simultaneous raids culminated an 18-month investigation dubbed Project Tandem.

Stewart said the operation focused on the criminal activities of the Hells Angels, including trafficking of illegal substances and weapons, counseling to commit murder and criminal organization offences.

Property seized during the raids includes vehicles, weapons and illegal drugs.

Station beefs up security

Police have increased security outside the east-end Toronto police station where suspects will be processed as they're brought in from across the GTA.

Uniformed police officers are standing guard over the entrance to a vehicle compound in the back of 42 Division in Scarborough.

A list of suspects and charges has not been released. Police said the information will not be made public until Friday.

Called the the largest outlaw motorcycle gang in Canada, the Hells Angels moved into Ontario in 2000.

It is believed there are at least 100 members in the Toronto area, the highest concentration of the biker gang in the world.

Vagabonds are another Ontario-based motorcycle gang, but they were mostly absorbed when the Hells Angels moved into the province.

The OPP, the RCMP, the Toronto police and officers from the regions of Halton, Hamilton-Niagara, Peel, Windsor and York took part in the raids.

With files from Canadian Press