OAKLAND, California: The Hells Angels motorcycle club, which in the 1960s became synonymous with the U.S. outlaw biker counterculture, plans to celebrate its 50th birthday this weekend, and police are putting extra officers on duty. But police downplayed the chance for trouble.

The club's Oakland chapter is best known for providing security at a 1969 Rolling Stones concert during which a Hells Angel member killed a fan, an incident captured in the 1970 documentary "Gimme Shelter."

George Christie, the group's Ventura chapter president, said the party is drawing members from all over the world.

"I anticipate it's going to be one of the biggest events the club has had," he said. "I just think everybody's in a festive mood."

Even so, the concert "stigma" still follows the group, he said. The Hells Angels were given free beer to help keep fans from rushing the stage. When a shouting match erupted as The Rolling Stones played, fan Meredith Hunter pulled a gun and was stabbed by Hells Angel member Alan Passaro.

Passaro, who died in 1985, was acquitted after claiming self-defense.

The Hells Angels, which formed in 1948, organizes motorcycle runs all over the world and takes part in charitable events such as Christmas toy drives, but it has a long history linking it to methamphetamine distribution, prostitution and violence.

Earlier this month, 11 chapter members were sentenced to prison in connection with a deadly brawl with rival Mongols biker gang members in a Nevada casino in 2002. However, federal charges against three dozen other members were dismissed after prosecutors failed to prove the club was a criminal enterprise similar to the Mafia.

The Oakland chapter was founded by Ralph "Sonny" Barger, 68, who served time in federal prison for conspiring to blow up the clubhouse of a rival biker gang, the Outlaws.

He has since become a best-selling author, but his lawyer said he was unavailable to comment and refused to give details of the weekend's events, describing it as a "private party."