Olympic champion Jack Laugher has criticised British Diving after his coach Adrian Hinchcliffe left to join the Australian team because he was not offered a full-time contract.
Hinchcliffe claims he was left with "no option" but to take-up the Australian offer after his requests for a permanent role in Britain were unsuccessful.
The coach guided Laugher and team-mate Chris Mears to Britain's first ever Olympic gold medal in the sport in the 3 metres synchronised event at Rio 2016.
Laugher also took silver behind Cao Yuan of China in the individual 3m springboard final.
At the time, Hinchcliffe was employed by Leeds City Council and was only working for British Diving as a consultant.
"He's achieved things as a coach that no-one in this country has ever done before and it's a massive insult to me and to Ady [Hinchcliffe]," Laugher told BBC Look North.
"British Diving and the national performance director [Alexei Evangulov] have really overlooked how much of a key part he is.
"To have someone like Ady say 'sack this I'm leaving', well it should never have got to this point."
Hinchcliffe also coached several other members of the British team, including Commonwealth champion Rebecca Gallantree and Daniel Goodfellow, winner of a 10m synchronised Olympic bronze at Rio 2016 alongside Tom Daley.
Daley's current coach Jane Figueredo is employed by British Diving on a full-time contract.
"To really help those like Jack and Chris as well as the other superstars we had out in Rio keep improving, I needed to be in a full-time role," Hinchcliffe told the BBC.
"Coaches tend to be humble by their nature - it's the athletes who go up on the podium - but it's such an important role.
"British sport is so successful at the moment and we need to examine all of the components behind that, but in my particular case I just don't think that's happened."
British Swimming, the national body for aquatic sports in the country of which British Diving is part of, have admitted to being "disappointed" by the decision.
"We were aware that he wanted to work with the sport full-time and we were in the process of beginning discussions but unfortunately timescales didn't allow these to conclude," they said.
"We'd like to thank him for all of his hard work and dedication, and we wish him well for the future in Australia."
Britain were the only nation other than China to win a gold medal at Rio 2016.
Australia won a solitary women's 3m synchronised bronze medal but will now look to close the gap at the Commonwealth Games in Gold Coast in 2018.