Gyarfas, the former Hungarian Swimming Federation (MUSZ) President who serves on the eight-person FINA Executive, was detained by police in connection with the investigation, according to state news agency MTI.

Fenyo, who owned a portfolio of newspapers and magazines and a television network, was gunned down while in his car in February 1998.

Slovakian Jozef Roháč was sentenced in life in jail for the killing of Fenyo, who Gyarfas considered a rival, in May of last year.

They did not say who ordered the murder, however, and Hungarian police decided to reopen the case last October.

So far, no-one has been charged with ordering the killing.

MTI named Gyarfas as one of two men who were questioned and arrested as part of their ongoing investigation.

The 69-year-old has been a controversial figure in Hungarian swimming in recent years and resigned from his role at the helm of the MUSZ in 2016.

He stepped down from a position he had held since 1993 following pressure from athletes such as three-time Olympic champion and multiple World Championships gold medallist Katinka Hosszú, who called for him to quit.

A catalogue of problems were alleged by swimmers, including Hosszú.

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

Training conditions within Hungary have worsened since 2015, she said, to the extent that top swimmers often have to train "at zero degrees, many times in the pouring rain in an outdoor pool".

Her comments were echoed by Hungary's International Olympic Committee Athletes' Commission member Daniel Gyurta, who wrote on Facebook that there is "no order" around the MUSZ.

"FINA is aware of the media reports regarding FINA Executive member, Tamas Gyarfas," FINA said in a statement to insidethegames.

"We will continue to monitor the situation closely as we await for further developments of the ongoing investigation."