Los Angeles - A trio of world and Olympic champion swimmers has sued swimming's world governing body FINA in a US court in San Francisco over its crackdown on non-FINA approved events.

Hungarian Katinka Hosszu and Americans Tom Shields and Michael Andrews filed the class-action anti-trust lawsuit on Friday after Swiss-based FINA effectively shut down an independent meeting in Italy, threatening to ban elite swimmers who took part from Olympic competition.

The meeting, scheduled for late December in Turin, Italy, was coordinated by organizers of a proposed International Swimming League that would operate outside FINA's control and pay higher prize money.

Shields, an Olympic gold medalist, said he joined the lawsuit because he had dreamed for years of seeing swimming expand to include a professional league.

"We are closer now than ever before to making that dream come true," Shields said. "But that dream is being blocked by FINA."

Attorneys for the plaintiffs say the swimmers "believe a professional league that will compensate its best athletes and better reward them for a lifetime's worth of hard training and sacrifice is long overdue."

The lawyers said that the International Swimming League had filed a separate lawsuit against FINA for its alleged "anti-competitive conduct."

Although neither lawsuit challenges FINA's authority to operate as the gatekeeper of the Olympic Games, the lawyers said, they allege that FINA "unlawfully wields that power to prohibit swimmers from participating in non-FINA events or in any events that FINA does not formally approve."