Brazilian authorities investigating Olympic official Carlos Nuzman in a vote-buying case have asked for help from prosecutors in Switzerland, where he is believed to have stored gold bars.
The office of Switzerland's attorney general said on Friday it was analysing the request for legal assistance.
"The request has been transferred from the Federal Office of Justice (FOJ) to the (attorney general's office) as the competent authority for execution," the federal office said in a statement.
Nuzman was arrested on Thursday in Rio de Janeiro on suspicion of obstructing the investigation, one month after being detained and questioned by Brazilian and French authorities. Prosecutors also believe he stored 16 bars of gold in a depository in Geneva.
As Brazilian Olympic Committee president, Nuzman led the 2016 Olympic bid and organising committees.
Prosecutors have implicated Nuzman in a bribery scheme of at least $US2 million ($A2.6 million) to help win votes from IOC members, who chose Rio as host city in 2009 in a four-city contest. The losers were Chicago, supported by then-President Barack Obama, Madrid and Tokyo.
The International Olympic Committee - based in Lausanne, Switzerland - is considering a provisional suspension for the 75-year-old Nuzman. He is an honorary member after passing the 70-year age limit.
Nuzman also sits on an IOC panel overseeing preparations for the 2020 Tokyo Olympics.
Brazilian prosecutors believe Nuzman was a central figure in channelling at least $2 million of a Brazilian businessman's money to Lamine Diack, a former IOC member from Senegal who helped control African votes.
Diack has been arrested in France as part of a wider case of alleged corruption while he was president of track and field's governing body, including blackmailing athletes to cover up doping cases.
The French case has also implicated four-time Olympic sprint medallist Frank Fredericks of Namibia. He was an IOC executive board member in October 2009 when he received a $US300,000 ($A386,000) payment linked to Brazil and the Diack family on the day Rio won.
On Thursday, Brazilian authorities said Nuzman's net worth increased by 457 per cent in his last 10 years as the country's Olympic leader.
Nuzman was arrested because investigators found he tried to hamper the investigation by regularising assets likely gained with illicit money. Last month, he allegedly amended his tax declaration to add about $US600,000 ($A772,000) in income.
Nuzman's lawyers said he denied wrongdoing, and the IOC said he had the presumption of innocence while its ethics commission studied the case.
