Police and prosecutors in the German financial hub of Frankfurt have uncovered an international fraud ring alleged to have defrauded bank customers of millions of euros.

Together with authorities in Brazil, they dismantled a criminal network after several years of investigation and arrested numerous suspects, the Federal Criminal Police Office (BKA) and the Frankfurt Public Prosecutor's Office said on Friday.

According to a statement, three suspects in Europe have been identified on suspicion of computer fraud in online banking. They will now be prosecuted in Spain and Bulgaria.

Brazilian authorities, supported by the BKA, also carried out a major operation against the network on Thursday. Four suspected members were arrested and 21 properties in seven cities were searched.

The suspects are accused of carrying out numerous unauthorized withdrawals from the accounts of German online banking users in just a few days in November 2023.

"The extent of the damage is in the millions," the authorities said.

The group reportedly exploited a vulnerability in the booking process at a payment service provider, which was caused by a faulty software update.

Misappropriated funds were then mainly transferred to Brazil, where a large portion was paid out after attempts to conceal the identities of recipients.

The gang conducted similar transactions in four European countries. The findings of the Brazilian authorities will now be incorporated into the investigation in Germany.

The successful outcome shows that cybercriminals cannot rest easy, said Senior Public Prosecutor Benjamin Krause, who heads the Central Office for Combating Internet Crime (ZIT) at the Frankfurt Public Prosecutor's Office.