(Reuters) – Three world-class swimmers have filed a lawsuit in the United States, challenging what they allege is the monopoly world governing body FINA has over the control of international competitions.

The lawsuit, brought on behalf of three-times Olympic gold medalist Katinka Hosszu of Hungary and U.S. world champions Tom Shields and Michael Andrew, followed the cancellation of a new professional swimming event scheduled for Dec. 20-21 in Turin.

“FINA’s insistence that the world’s best swimmers may compete only on FINA’s terms and its efforts to enforce that rule are nakedly anti-competitive,” said the lawsuit which the trio said was filed “on behalf of elite swimmers around the world”.

The Italian federation said FINA had threatened sanctions against those swimmers taking part in the event, which was put together by organizers of the International Swimming League (ISL).

The world governing body, in a statement, said it had taken note of the filings in California.

“As world and Olympic champions, the swimmers in question will understand that FINA’s attention is focused on the 950 swimmers, including two of the athletes in question, from 180 member federations taking part in the 14th World Swimming Championships in Hangzhou,” FINA said.

“FINA will nonetheless give the filings our full attention and mount a robust defense if required to do so. Meanwhile in Hangzhou, the FINA Athletes Committee will consult with aquatics athletes to continue its work of making sure athlete voices are clearly heard within FINA’s decision-making bodies.

“FINA remains open to proposals that would enhance – rather than conflict with – current and planned competition calendars, providing further opportunities for aquatics athletes, and ideally in a manner that benefits the whole sport.”

The governing body had said in November the Turin meeting did not meet their rules requirements.

“The project of the Italian Swimming Federation to organize a swimming competition in Turin at short notice did not meet all the necessary FINA rulebook requirements.”

The ISL is proposing to organize meetings outside the control of FINA and pay higher prize money.