The 28-year-old Hungarian, winner of gold medals in the women's 100 metres backstroke, 200m medley and 400m medley at Rio 2016, has penned an open letter that she has posted on Twitter. 

In the letter, Hosszú claimed that "if swimming is still not a professional sport, then that is a reflection of the work FINA has been doing for the past few decades, not a reflection on the sport that is one of the fundamentals of childhood athletic development".

The three-time reigning FINA women's Athlete of the Year added: "It’s not an exaggeration to say that FINA is in chaos.

"There is the lack of transparency in the financials, the constantly changing rules, and leaders with no vision.

"At first it may seem a bit scary, but this is the time for us, the swimmers, to do something about the future of our sport.

"We wouldn’t need to be pioneers; there are so many inspiring examples from other sports before us.

"Based on regulations in the NBA (National Basketball Association), the league has to give more than half of the yearly basketball-related income to the athletes; exactly 51 per cent goes to the athletes as salary, not more, not less.

"Therefore both the league and the athletes have the same motives.

"This system is transparent and fair.

"Do you know why the league is set up this way?

"Not because the leadership of NBA was so generous and offered a percentage of the basketball-related income as a gift.

"It’s because the players recognised the power of being united and the NBA had to realise that without the players the league would be worth nothing."

Hosszu’s argument focuses on recent rule changes to the FINA World Cup series, limiting competitors to four individual events per meet. 

FINA claimed the changes have been made to "attract more stars and improve the exposure and visibility" of the competition.

Alterations include Olympic and World Championship medallists having direct access to finals and a maximum of 25 events per leg.

FINA also promised there will be increased financial rewards for each race with swimmers competing for prize money of $3,900 (£3,100/€3,500) per race.

The overall amount of prize money available could rise to $2 million (£1.6 million/€1.8 million).

It is the change that allows swimmers to only enter a maximum of four individual races per leg, though, that has angered Hosszú the most.

The "Iron Lady" has dominated the World Cup in recent years, finishing top of the women's standings in the last five editions after entering into almost every discipline.

In a post on Twitter, Hosszú said the move was "ridiculous" and that "swimming is going backwards". 

Athletes will, however, be able to enter relay events on top of their individual races.

For winning last year's women's and men's overall World Cup titles respectively, Hosszú and Russia's Vladimir Morozov received $100,000 (£79,000/€90,000) in prize money.

"First of all, they should reach out and listen to us, the swimmers," Hosszú, a five-time long-course world champion, said in the letter.

"They should hear us out and not decide upon major rule changes without our input on the topic.

"If they would have asked for our opinion, we could have told them that the World Cup has huge potential, but the planned new rule changes are destructive and hypocritical.

"Everyone thinks that the new World Cup rule changes are against Katinka Hosszú.

"That can be partially true, because they definitely screwed me over.

"Imagine, I’m like one of those students that got straight As in every class, plus took-on drawing and chorus as extra-curricular activities.

"Then, the next year I’m told I cannot do extra-curricular activities because my success was bothering the rest of the students.

"The real truth, however, was that it was only the teacher who was bothered.

"I could view myself as a victim, but, on the other hand, I get advantages from FINA that I never requested.

"I don’t want to automatically advance to the finals of the World Cup competitions based on my previous results at international competitions.

"I want to race for the final spots with young talents and if they are better than me at the age of 14, let them show their talent.

"With the new World Cup rule changes, they have to start from a disadvantage - they have to wait until the sport’s top athletes get old or finish their careers before they can have the advantage of automatic advancement to finals.

"This is just not fair."

When asked about the changes in an interview with ZRT ATV, FINA executive director Cornel Marculescu claimed the new rules will "stimulate the participation of the best athletes".

He also revealed the changes would be reviewed after one year and declared it was FINA's Technical Committee that were responsible for the move and that FINA vice-president Tamás Gyárfás was not involved.

Gyárfás resigned as President of the Hungarian Swimming Federation in November following criticism from the country's top stars after 23 years in the post, with a catalogue of problems alleged by swimmers.

Hosszú claimed her relationship with Gyárfás had been adversarial ever since he supposedly urged her to "stop swimming and retire" in 2008.

Other changes to the World Cup include enhanced sport presentation and television production at every event, additional promotional activities on-site involving athletes and medal ceremonies will be held at the end of each day.

Hosszú is not the first swimmer to raise the idea of a worldwide professional union.

Previous efforts in Olympic sports have generally failed because of an inability to engage leading athletes publicly.

Held between August and November, this year’s FINA World Cup series will comprise of nine legs split into three clusters.

The first leg is due to take place in Russia's capital Moscow between August 2 and 3. 

insidethegames has contacted FINA for comment on the contents of Hosszú's open letter.