Virgin Media has warned 1,500 customers that their PC has been infected by malware.
The Serious Organised Crime Agency (SOCA) alerted the broadband firm to the IP addresses of machines infected with the SpyEye Trojan, and as a result Virgin Media informed those customers via a letter, which also contained information on how to remove the malware. The ISP, which launched the initiative to warn users last year, was keen to stress it had not been tracking its customers' activity.
The SpyEye Trojan steals personal and online banking information from the machines it infects. Virgin Media likened the Trojan to 'Zeus' - the banking Trojan that last year was thought to have stolen around £20m.
Jon James, executive director of broadband at Virgin Media, said: "Cybercrime is on the rise and the increasing sophistication of malware infections mean that all internet users could be at risk with devastating effects.
"We are taking this proactive approach to help protect our customers and to provide them with the support and advice they need to stay safe online so that they can enjoy the best of the internet without the worry."