THE Hells Angels in Sydney have secured what may be the greatest mass defection in the history of the Australian outlaw clubs, recruiting at least 50 members from rival gangs.

Police fear the defections - involving at least three Bandidos chapters in NSW - may lead to a new war between bikie gangs. It could be the most significant event since the Comanchero split of 1982, which led to the Milperra massacre two years later when seven people, including a 14-year-old girl, were shot dead.

''We've had small numbers move around before but this number is unheard of,'' a senior law enforcement source told The Sun-Herald.

The underworld has been abuzz since a deal, apparently months in the making, was cemented 11 days ago. Between 50 and 60 men left the Bandidos and joined the Hells Angels.

It is understood the deal was organised by Felix Lyle, a rising force within the Angels and a former Bandido. Offers to defect and join the Angels were also made to other clubs.