Brazilian police have arrested an individual suspected of leading a phishing gang that stole $37m from its victims' online bank accounts.

It is claimed that the gang, which included more than 18 people, stole from online banking customers using a Trojan sent to thousands of computers via email.

The head of the police department in charge of internet fraud in Brazil's Santa Catarina state believes that the arrested man, Valdir Paulo de Almeida, headed up one of Brazil's biggest gangs.

"They moved between 50m and 100m Brazilian reais [£9.6m and £19.3m] over the past two years [and] sent over three million emails with Trojans per day," he said.

According to security firm Sophos such Trojans are increasingly being used as a phishing device to steal money.

Once a computer is infected with a Trojan, internet activity is monitored and when a banking website is accessed, confidential data can be transferred to fraudsters.

Graham Cluley, senior technology consultant at Sophos, said: "This is the latest arrest of phishers in Brazil. Last year, more than 50 arrests were made [in October] and in February, a gang of four were arrested. It's great that the Brazilian authorities are stamping down on internet fraudsters.

"Most computer users are aware of the threat from phishing emails that direct online bank users to fake websites, but some are still unaware of the threat from Trojans which can surreptitiously steal hard-earned cash without any warning.

"By protecting their PC with updated antivirus software and a firewall, and exercising caution, computer users can continue to enjoy the benefits of banking online."