Citibank has warned its customers not to fall for an e-mail scam that threatens to shut down their current accounts unless they provide their social security details.
In statement, Citibank says it is working with law enforcement to investigate the fraudulent e-mail, which has been sent as spam to numerous addresses.
The email tells recipients that their current account will be suspended unless they accept new terms and conditions and directs them to a site that appears to be Citibank's. The fradulent site requests the customers' name and the first four digits of their ATM card number.
Citibank says: "Although the e-mail appears to come from Citibank regarding 'Your Checking Account at Citibank,' it does not, and Citibank is in no way involved in the distribution of this e-mail."
The bank says its systems have not been compromised and has urged customers to delete the e-mail and call customer services.
The e-mail is an example of 'phishing' - which uses spam e-mail to direct users to fake Web sites in order to deceive them into giving personal financial data.
Citibank is the latest bank to be targeted by fraudsters. Latvia's Hansabank, the Commonwealth bank of Australia, ANZ, Westpac, Bank of America and Spain's Banco Bilbao Vizcaya Argentaria (BBVA) have all been targets of Web banking scams in recent months.