Online banking customers have been warned to be on the alert for a fresh wave of phishing e-mail attacks in the wake of the banking turmoil.

Fraudsters are taking advantage of the uncertainty surrounding British banks to trick users into logging into false websites with the intention of stealing their personal details.

Apacs, the bank payments industry association, said that it was aware of several fraudulent e-mails targeting customers of Lloyds TSB, HBOS and Barclays.

A phishing attack typically involves fraudsters setting up a fake version of a genuine bank website, and then sending out spam e-mails trying to convince people to click on a link that will lure them to that fake site.

The objective is to fool people into entering their online banking security information – such as user names, PINs and passwords – on the fake site. The stolen information is often sold on to people who raid the bank accounts and commit ID fraud.

One example, understood to be from the fraud prevention unit at Lloyds TSB, told customers that the bank was making an extra security check on customers in response to its merger with HBOS, and asked them to confirm their online banking details. The e-mail added that “failure to do so may result in temporary account suspension”.

A spokesman for Apacs said: “The organised criminal gangs behind phishing attacks have begun to focus on bank mergers and the economic down-turn as the reason for asking people to disclose their security details. As ever, our advice is that your bank would never contact you in this way and ask you for your PINs, login details or passwords. If you receive an e-mail of this nature you should simply delete it.”

Phishing criminals are increasingly tailoring their attempts to real-life incidents to make them more credible.

Cyber-criminals are known to track the search trends on Google to produce more appealing phishing attempts.

Rik Ferguson, of the online security company Trend Micro, said that such “social engineering” attacks were related to significant news events, such as Hurricane Gustav. He added: “When the Russia-Georgia conflict blew up, there was a slew of phishing e-mails saying that Russia had fired nuclear weapons at Georgia and that World War III had started. Unsurprisingly, a lot of people clicked on the link.” In the United States, fraudsters have targeted online banking customers of Washington Mutual and Chase Manhattan, who received e-mails asking them to verify their account information. The US Federal Trade Commission said that it expected fraudsters to pose as the new owners of banks or the government agencies charged with oversight of struggling institutions.

There were more than 20,682 phishing incidents in Britain in the first six months of this year, an increase of 186 per cent on the same period last year, according to figures released by Apacs. This sharp rise helped to push online banking fraud losses to more than £21 million over the same period.

The code produced by the British Bankers’ Association makes it clear that banks may not be responsible for losses on online bank accounts if consumers do not have up-to-date antivirus and firewall software installed on their computers.

Banks are also arguing that customers who hand over their details to a phishing website are guilty of negligence, giving the bank grounds to refuse refunds.

Avoid becoming a victim

— Check and understand how your bank communicates with you – by e-mail, post or telephone

— Assume that any e-mail that either directly asks or indirectly asks for your account, financial, or identity information is not to be trusted

— If you do online banking, always type in the bank URL into your browser or set it up as a favourite. Never click on a link in an e-mail

— Check your credit card statements for incorrect expenditure