Almost four decades after the Hell's Angels terrorised America and inspired the classic Hunter S. Thompson book of the same name, US authorities have declared war on an outlaw motorcycle gang.

But times have changed since the Sixties - when details of biker atrocities were printed in Time magazine and the Hell's Angels were hired to provide “security” at rock concerts such as the Altamont Speedway Free Festival, at which an audience member was fatally stabbed during a Rolling Stones performance.

For a start, it is no longer the Hell's Angels who are causing havoc. That honour today goes to the rival Mongols gang, formed in southern California during the Seventies by Latinos who were barred from the Hell's Angels because of their skin colour.

The authorities of forty years ago tried to shut down biker gangs with the Rico Act - originally designed for the Mafia. Today's law enforcement officials are doing something more suited to an era in which bikers are just as likely to be software executives (the so-called Rich Urban Bikers) as criminals: they are trying to commandeer the Mongols' trademark name.

An injunction being sought by Thomas O'Brien, a lawyer, would make it illegal to wear clothing that features the group's logo. “It would allow law enforcement to seize the leather jackets right off their backs,” he said.

The Mongols are named after the nomadic tribes of northeast Asia and their website quotes Genghis Khan, the founder of the Mongol Empire.

The attempt to wrest control of the Mongols brand is part of a wider assault by the Bureau of Alcohol, Tobacco, Firearms and Explosives (known as the ATF), which accused the 600-strong organisation yesterday of being involved in murder, torture, drug trafficking and other offences.

The ATF also said that it had infiltrated the group with four undercover agents, resulting in the arrest of 61 members of the club in the states of California, Nevada, Oregon, Colorado, Washington and Ohio. Among those held were the gang's former national president, Ruben “Doc” Cavazos, the author of a memoir called Honor Few, Fear None: The Life and Times of a Mongol, published this year.

“The organisation from top to bottom has been charged and targeted,” Michael Sullivan, acting director of the ATF, said. “It puts a stake in the heart of the Mongols.”

Some prominent Mongol supporters remained defiant yesterday. Roger Pinney, a Vietnam veteran and former national president of the club, said: “This is all going to blow over. The Mongols aren't going away, and neither are the Hell's Angels.”

Pinney is on probation for his part in a 2002 brawl in which three bikers died.

According to the ATF, its undercover agents were accepted into the gang only after lie detector tests and checks by private detectives. As part of the sting, the agents were given false identities and social security numbers. They started by doing menial duties for the gang, including security work at parties, while living away from their families with female undercover agents, who pretended to be their biker girlfriends (women are not allowed to be full members of the gang).

The agents later became “full-patch” members, meaning that they could wear the group's insignia.

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