Federal police in Brazil say they have arrested more than 50 people for allegedly stealing $30m (£16m) from Brazilians through internet fraud.
Hacking itself is not a crime in Brazil
They said the arrests were made across four states in the north of Brazil.
The group secured the money by sending e-mail attachments infected with a virus able to store details of people's internet bank accounts, police said.
Computer fraud experts said last month Brazil was now the global capital of hacking and internet fraud.
Cristiano Barbosa, who co-ordinated the operation which resulted in 53 arrests, told the Jornal do Brasil newspaper: "They diverted money from e-mail accounts across the country - mainly in the south or south-east where people use e-mail more frequently."
At a conference in the capital, Brasilia, in September, federal police said the country was home to eight out of 10 of the world's hackers.
The amount of money lost in internet financial fraud in Brazil outstripped that lost through bank robberies, the conference was told.
And security experts from other countries said some 96,000 hacking attacks were launched from Brazil last year - six times more than any other country.
The explosion in hacking was blamed, in part, on weak legislation.
Police have to prove fraud has taken place in order to prosecute, as hacking itself is not a crime in the country.