INTERNET fraudsters are using an audacious double bluff to rob people of their cash: spam e-mails give warning of the risks of responding to unsolicited mail that asks customers to disclose internet banking log-in details — before inviting would-be victims to do just that.

Customers of Barclays have been a recent target of this scam. The fake Barclays e-mail states: “Some customers have been receiving an e-mail claiming to be from Barclays, advising them to follow a link to what appears to be a Barclays website . . .

Barclays is in no way involved with this e-mail and the website does not belong to us.”

After attempting to gain the trust of their victim, the fraudsters move in for the kill: “Barclays is proud to announce about their new updated secure system. We updated our new SSL servers to give our customers a better, fast and secure online banking service. Due to the recent update of the servers, you are requested to please update your account information at the following link.”

The emergence of phishing e-mails that use internet security fears to trick potential victims comes after research from Gartner, a technology research company, found that phishing gangs were achieving a better response rate than direct marketing companies. Phishing e-mails typically elicit replies from between 3 per cent and 5 per cent of recipients. The click-back rate from direct mail is just 0.5 per cent.

Internet service providers are having to develop new systems to counter the threat. Times Money can reveal that BT Yahoo! Broadband is pioneering technology that will block phishing e-mails sent to its e-mail subscribers. The system is expected to go live this summer.

MailFrontier, the internet security company, reported a rise in phishing cases from 1,082 in April last year to 13,482 in March this year. MailFrontier has compiled a quiz to help worried consumer to spot a phishing e-mail; contestants must decide whether e-mails from ten companies are legitimate or just phishing.

Jack Blockley, chief operating officer of Geneva Partners, a technology consultancy, says that phishing is a successful formula for fraudsters. He says: “If you throw enough mud at the wall, something will stick. If you send out 100,000 e-mails and 2 per cent of those targeted reply, you can steal thousands.”

Internet fraud cost the banks £12 million last year and industry sources say that high street banks have been taken aback by the scale of their losses this year. In a belated attempt to counter the threat, Barclays, HBOS, Royal Bank of Scotland and NatWest have delayed instantaneous online bank transfers by between several hours and a day.

But it is not just unwary bank customers who have made phishing so profitable. Internet security experts have given warning that anti-spam filters, which home in on the scatological words synonymous with unsolicited e-mails, are failing to stop phishing e-mails that use the lexicon of our high street banks.

Sandra Quinn, a spokeswoman for the Association for Payment Clearing Services, (Apacs), a body that represents the banks on payment issues, says that fraudsters have discovered that the best way to disguise their criminal intent is to use the cloak of internet security. But she adds: “Your bank does not, in any shape or form, ask you to disclose security details in an e-mail. Customers should delete unsolicited mail.”