'Significant result'

They are suspected of being members of an online group called M00P, delivering the viruses as attachments on unsolicited e-mails known as spam.

The arrests follow a joint operation between the Metropolitan Police and officers in Finland.

Detective Constable Bob Burls, of the Met Police's computer crime unit, said: "The international co-operation between the specialist law enforcement units has produced this really significant result.

"We believe the suspects created and adapted viruses with the aim of causing massive infection by spamming."

He said he hoped the arrests would send a "clear signal" that national borders would not stop the authorities taking action over malicious computer software.

Police have raided residential addresses in both the UK and Finland and seized a number of computers and computer servers.