Switzerland has frozen around SFr50 million ($36 million) allegedly laundered by Brazilians.
Swiss authorities said the money was at the centre of a corruption investigation in Brazil.
Andrea Sadecky of the Federal Prosecutor's Office confirmed to swissinfo that the money had been blocked in several banks following a request from the Brazilian authorities for judicial assistance.
Switzerland has been investigating the case since August last year and is trying to ascertain whether the accounts contain laundered cash.
Sadecky said she could not give any other details about the case, which involves ten individuals.
She also declined to say whether the money was linked to a corruption investigation in Rio de Janeiro, where four state tax inspectors have come under scrutiny for extorting millions of dollars deposited in Swiss bank accounts.
The inspectors and four federal officials are accused of accepting about $23 million in bribes in exchange for turning a blind eye to tax evasion by several of Rio de Janeiro's largest companies.
The companies under investigation have not been identified.
The case came to light in December when Swiss prosecutors alerted Brazilian authorities that the officials were apparently laundering the money in Switzerland.
Meanwhile, the Swiss justice authorities have decided to hand over to Nigeria files they collected in a money-laundering investigation, relating to the late Nigerian dictator, Sani Abacha.
On Tuesday, the chief prosecutor of canton Geneva, Daniel Zappelli, said the move was necessary because all surviving principal suspects lived in Nigeria.
"The Nigerian government prefers not to let them leave the country," Zappelli said. "It comes down to a choice between a trial in Geneva without the accused or a trial in Nigeria in the presence of the accused."
The Abacha case, which came to light in 1999, is seen as a particular embarrassment for the Swiss authorities.
It is the biggest money-laundering scandal to have hit Switzerland involving a foreign head of state.
swissinfo, Andreas Keiser
Switzerland has frozen SFr50 million in bank accounts.
The money was blocked following a request from Brazil.
Switzerland has been investigating the case since August.
Swiss authorities also decided to hand over files to Nigeria related to the Abacha case.
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