International Swimming Federation (FINA) Bureau member Coaracy Nunes has been removed as President of the Brazilian Aquatic Sports Confederation (CBDA) as part of an investigation into corruption and fraud.
The 78-year-old, head of the national governing body since 1988, is one of four officials removed from office by Brazil's Federal Public Ministry.
They claim to have discovered "strong evidence" of overbilling, misappropriation of public funds and embezzlement.
Allegations include that funds designated to buy equipment for the Brazilian Olympic team have been misused,
An increase in funds allocated for airline tickets is also being investigated, while police believe that one of the companies that they have done business with, Natação Comércio de Artigos Esportivos Ltda, is actually a front company used to illegally divert public money.
The organisation's vice-president Luiz Soares has also been ordered to be removed from office by the Federal Court of São Paulo following the Public Ministerial request, Globo has reported.
Three other officials, Sergio Alvarenga, Ricardo Moura and Ricardo Gomes Cabral, have also been sanctioned.
Nunes has denied all allegations, claiming the charges are being instigated by opponents hoping to oppose him in fresh elections scheduled for next year.
A lawyer for the CBDA also claims to be "outraged" by the decision-making process, Globo reported, claiming the defendants were not provided with enough information.
"We are told by the press, preventing the right of defense," they reportedly said.
They plan to appeal.
Open water swimmer Poliana Okimoto's bronze medal was the only Brazilian podium finish in an aquatics event during an otherwise disappointing Olympic Games in Rio.
insidethegames has contacted FINA to ask if Nunes will be suspended from his Bureau position.
The official is a longstanding member of the ruling panel and also served as Swimming Union of the Americas President between 2011 and 2015.