A new type of malware is specifically targeting UK online banking customers, security experts have warned.
The malicious software retrieves online baking information and credit details from unsuspecting customers, and uses them to make unauthorised money transfers to anonymous bank accounts.
Security firm Trusteer explained that it had unearthed two Zeus botnets attacking customers of UK banks, and that the attacks are highly focussed, targeting customers of only three to seven banks at a time.
Mickey Boodaei, CEO of Trusteer, said: "This indicates a shift in financial criminal activity and requires some special attention from financial organisations. In the UK, each campaign would usually focus on three to seven banks and target them for a period of six to nine months."
The company has advised UK banks to share information and work together the deflect botnet attacks on their customers.
UK banking customers are not the first to suffer from this type of attack. Trusteer says similar attacks have been carried out in both Germany and South Africa.