Halifax/Bank of Scotland (HBoS) has cut virus infections by 90 per cent by using several suppliers for its antivirus strategy.

Under the new approach each layer of the bank's IT infrastructure is now protected by software from a different company.

Richard Fry, head of malware defence at HBoS, told vnunet.com that this acts as a failsafe should one vendor fail to update its antivirus signatures fast enough after an outbreak.

"It minimises risk from five per cent to one per cent," he said. "There are other companies with single-vendor multi-layer [coverage] and both [methods] work, but it is generally accepted that a multi-vendor approach is more secure."

Fry explained that the bank has cut virus incidents from 3,000 to 300 a month and that it is two years since the last "significant" infection of the bank's systems, which was the mass mailing 'lifestages' worm.

HBoS switched suppliers for the protection of 50,000 desktops and 5,000 servers earlier this year from Dr Solomon to McAfee.

The transport layer of 100 Microsoft Exchange and Lotus Notes email servers is covered by scanning and antivirus software from Trend Micro and, at the network gateway, the bank uses an email firewall product called WorldSecure.

Fry, who heads a team of three that monitor and manage the antivirus software, would not disclose how much the strategy had cost but stressed that return on investment was not an issue.

"If we switched off all our antivirus software we would probably last about six hours," he said. "So how do you put a cost on that?"

He explained that the bank is now using the new strategy "in anger" after a steady rollout over the past 12 months.

HBoS was formed from the merger of the Halifax and Bank of Scotland last September and is on target to achieve IT cost savings of £150m a year that will contribute to overall annual group savings of £620m.