LONDON: Police have arrested 19 people on suspicion of taking part in an online fraud that hit thousands of customers of some of the world's biggest banks, a police spokesman said on Wednesday.

London’s Metropolitan Police said 6 million pounds was stolen from a number of unnamed major world banks in one three-month period. The final figure is expected to be much larger as the investigation continues.

Detectives said a criminal gang was suspected of infecting thousands of computers in Britain with malicious software that allowed them to access people's internet banking log-in details.

“We believe we have disrupted a highly organised criminal network which has used sophisticated methods to siphon large amounts of cash from many innocent people's accounts,” said Detective Chief Inspector Terry Wilson, from the Police Central e-Crime Unit, based at Scotland Yard.

The gang is believed to have used a Trojan, a type of computer virus, to capture people's personal details which they then used to transfer money from their accounts, he added.

Police arrested 15 men and four women in co-ordinated early morning raids across London on Tuesday. They were held under the Computer Misuse Act, Proceeds of Crime Act and the Fraud Act.

Two of them were also held on suspicion of possessing a firearm.

Detectives warned internet users to check their online security and said they should take extra steps to avoid a commonly used Trojan known as Zeus. – Reuters