Brazilian and French investigators announced on Tuesday they had uncovered an international corruption scheme centered on awarding the 2016 Olympic Games to Rio de Janeiro.

The head of the national Olympic committee was accused of arranging a $2 million (1.7 million) bribe to secure the games in the city, despite it having the worst conditions.

Federal Brazilian police said "there are strong indications" that committee head Carlos Alberto Nuzman had bought votes from fellow African members of the International Olympic Committee (IOC) in order for Rio to be chosen as the venue in 2009. Rio beat out Chicago, Tokyo and Madrid.

Police searched the headquarters of the Brazilian Olympic Committee and the home of its president Nuzman as part of the nine-month investigation, seizing computers and documents.

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Prosecutors said Nuzman was not arrested, but was detained to give testimony and had his passport confiscated. Authorities also issued an arrest warrant for Miami-based businessman Arthur Cesar de Menezes Soares Filho, who won lucrative pre-Olympics contracts from Rio's government when it was headed by the now imprisoned state governor Sergio Cabral.

Authorities issued a total of 11 detention warrants in both Brazil and France as part of "Operation Unfair Play."

IOC taken by surprise

The IOC appeared to have been taken by surprise when contacted by news agency AFP.

"The IOC has learned about these circumstances from the media and is making every effort to get the full information," its spokesman said.

"It is in the highest interests of the IOC to get clarification on this matter."

Papa Massata Diack, son of Lamine Diack, has denied any wrongdoing

Investigators accused Nuzman of bringing together Soares Filho and Lamine Diack, the former head of track and field's governing body and a voting member of the IOC at the time. They alleged that Soares Filho's company, Matlock Capital Group, paid $2 million into an account of Diack's son, Papa Massata Diack.

Read more: Rio's Olympic legacy: Corruption and people power

Prosecutor Fabiana Schneider said several construction and concession companies profited by bringing the games to Rio. She said the scheme was driven by the "criminal organization" of Sergio Cabral, the former governor of Rio de Janeiro, who has since been jailed on separate corruption charges.

"The Olympic Games were used as a big trampoline for acts of corruption," Schneider said.

Many large construction firms have been ensnared in Brazil's sweeping "Car Wash" anti-corruption investigation, which has uncovered a huge web of embezzlement and bribery at top levels of politics and business. The firms admitted paying massive bribes to politicians and former executives at state-run companies in return for contracts.

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The 75-year-old Nuzman was an IOC member for 12 years and was a prominent figure in Rio's bid for the games. He is part of the 2020 Tokyo Games coordination commission, which advises organizers in running the event.

Nuzman's lawyer, Sergio Mazzillo, said his client was innocent.

aw/bw (AFP, AP, dpa, Reuters)