They are the self-proclaimed baddest bikie gang in the world, and they have quietly orchestrated a takeover of an Australian gang.
It is believed up to 90 per cent of Finks gang members nationally have gone across to the US-based Mongols, while in Sydney close to 75 per cent of the club's 50 members switched over a fortnight ago.
The Australian links were further highlighted in an embarrassing aside, with revelations that Qantas and Telstra have been advertising on the Mongols' US website.
The reason for the patch-over is not being publicly disclosed but a source close to the club suggested it might be due to an internal matter.Police are also looking at whether it was a reaction to attempts to outlaw the Finks as an organisation in Queensland.
One bikie source said: "It's just a name change - they are just the Finks by another name. Any suggestion that it's going to lead to 100 Mongols flying out from the US to back them up next time they get into a stink is just ridiculous."
The United Motorcycle Council of NSW, set up four years ago and comprising most of the major bikie clubs, meets regularly to thrash out issues and is now headed by a Mongol.
But the expansion is being closely watched by NSW police, with the Mongols considered one of the most notoriously violent bikie clubs in the United States.
"If you look them up internationally, you will notice the Mongols have a major presence in the USA and Europe," gangs squad Detective Inspector Wayne Hayes said.
"They have quite a history of violence and criminal activity."
The Mongols boast a slick US-based website, which mentions four chapters in Australia and appears to be getting so much traffic it has attracted advertising from companies including Telstra and Qantas.
Last week the banner ads for Qantas on the website were offering cheap flights between Melbourne and Sydney, while News Ltd was offering digital subscriptions.
A spokeswoman for Telstra said an online publisher that the telco used to place its advertising was to blame and the ad would be removed.
"We employ a number of tactics, including a developing list of sites we will, and won't, advertise on," the spokeswoman said.
"Unfortunately on this occasion, our media was sent to this site without being cleared by us."
A spokesman for Qantas said the airline did not place the ad and it had ended up on the website as part of a package of advertising Qantas had done through Tourism Victoria.
It was "not the kind of website we would knowingly advertise on", he said. It is understood the ad has been removed from the site since Fairfax Media contacted Qantas.
Until a fortnight ago the Mongols' presence in Australia was largely unnoticeable. A chapter was quietly set up on the central coast two years ago, but its founder, Peter Emerton, said he no longer had anything to do with the gang.