Millions of people now control their cash via the web

The bank has signed a deal with F-Secure for 1.6 million licences of the Finnish firm's anti-virus program.

The deal also includes two years' worth of updates to ensure the security package keeps customers protected.

At the same time, the bank is bringing in a system that uses text messages to let customers know when money is moved using their online account details.

Security measure

Statistics gathered by the US National Cyber Security Alliance show that 56% of consumers do not have active anti-virus on their PCs, said Richard Hales, UK country manager for F-Secure.

Mr Hales said this meant many consumers were taking real risks with confidential data especially as the number of security threats was growing rapidly.

In the first four months of 2006, the number of items of malware, which includes trojans, worms and other malicious programs, seen by F-Secure had grown by 66,000, he said.

Barclays is sending letters to all 1.6 million online customers in the UK letting them know about the free software and giving them a code to unlock the program if they download it.

Once customers have downloaded and installed the software, it will automatically update to give protection against the latest threats.

The basic F-Secure anti-virus product protects against viruses and spyware. When installed it scans a machine and alerts users if it finds malicious programs installed.

A spokesman for Barclays denied that the deal was a way to limit its liabilities if customers were defrauded.

"We have a guarantee that if anyone is defrauded through no fault of their own we guarantee their money is safe," he said.

"We're trying to stop fraud happening in the first place which is beneficial to them and us," he added.

Barclays is the latest bank to try to stop customers falling victim to viruses or other computer-borne scams.

In October 2005, UK bank Lloyds TSB began issuing tokens that generate six-digit codes to be used alongside passwords and usernames.

The Alliance and Leicester has also introduced a system that tries to ensure that customers are the only ones that log in to their online account.