The banking industry has re-affirmed a policy that makes online banking customers responsible for losses if they have out of date anti-virus or anti-phishing protection.
New Banking Codes for consumers and businesses took effect on Monday.
The Banking Code produced by the British Bankers' Association (BBA), and followed by most banks, makes it clear that banks will not be responsible for losses on online bank accounts if consumers do not have up to date anti-virus, anti-spyware and firewall software installed on their machines.
"If you act without reasonable care, and this causes losses, you may be responsible for them," says the Code. "This may apply, for example, if you do not follow section 12.5 or 12.9."
Section 12.9 says: "Keep your PC secure. Use up-to-date anti-virus and spyware software and a personal firewall."
The BBA said that it was not aware that any bank had ever invoked that clause of the Code to avoid covering a consumer's online banking losses.
The new Code came into effect at the beginning of this week. The latest edition of the Business Banking Code took effect the same day.
Subscribers to the Banking Code must comply with it and are given until 1st July to ensure that their practices are in line with the code.
The Code contains a number of new provisions that the BBA says will help users of banks' services.
The BBA said that the Code strengthens credit assessment practices to ensure responsible lending. Some of the finance world's current troubles are widely blamed on its recent willingness to lend money to people without stringent enough checks or safeguards.
The Code also orders banks to provide clearer information about financial services products, as well as summary boxes for unsecured loans and savings accounts.
It also prohibits subscribing banks from closing customer accounts as a result of the customer complaining about the bank.
"The new banking code gives strong commitments that banks will lend responsibly and will help customers who may be heading towards financial difficulties,'' BBA chief executive Angela Knight.
The Code has been published as financial regulator the Financial Services Authority (FSA) said that it will investigate the treatment of homeowners who are falling behind in their mortgage repayments.
It said that borrowers with poor credit history are at risk of unfair treatment, and that it would investigate the situation and report in June.