Although police are playing down a big Hells Angels gathering in Calgary this weekend, an author who has written about the biker gang warned that they're still a criminal organization.

The bikers arecoming from across the country to mark the 10th anniversary of the setting up of the gang's Calgary chapter.

Local police and RCMP said Thursday they have a joint plan to keep the public safe, but wouldn't say whether they would be stepping up patrols or how they planned to monitor the event.

"We don't see it as a threat," said Insp. Luch Berti of the Calgary police.

"We just see it as a gathering of people that we've identified, just like the Red Mile or just like any other large gathering happening in the city such as the Stampede that just ended. We have a responsibility to the public and to the communities at large to make sure it's safe."

Julian Sher, the co-author of Angels of Death and other books about the Hell's Angels, said the biker gang sees the weekend more as a public relations exercise and predicted members would likely be on their best behaviour.

But Sher warned that it would not be a "Stampede on motorcycle wheels."

"These guys are criminals," he said. "This is the same gang that has killed people in the streets of Montreal, that has blown up buildings across the country. That's what's important for people to keep in mind."

It's estimated that there are about 500 full-fledged Hells Angels members in 32 active chapters across the country.

Police in various parts of the country were on the alert as Angels from other chapters began making their ways to Calgary.

Near Winnipeg, for example, the city police and RCMP set up a checkstop on Wednesday and pulled over several groups of the bikers. The police said they were stopping every vehicle with out-of-province licence plates, looking for outstanding warrants and vehicle violations.