A recently foiled bank heist in London has some security experts issuing heightened warnings about key-logging Trojans.

Security pros at Sophos Inc., an anti-virus and anti-spam company with U.S. headquarters in Lynnfield, Mass., is warning IT administrators to be on guard against keyboard-logging Trojans after reports surfaced that police shut down plans for a massive online bank robbery in London.

According to reports, thieves were trying to steal 220 million pounds from the London offices of a Japanese bank.

There has been speculation that these technically savvy suspects used a keyboard-logging Trojan to spy on desktop computers at the bank, capturing keypresses. The gang are said to have planned to transfer money electronically to 10 bank accounts around the world. Police in Israel are said to have arrested a man whose account had been the intended recipient of some of the money, but it appears the robbery failed and the bank suffered no financial losses as a result of the hacking, according to information from Sophos.

''More and more malware is being written by criminals, designed to steal bank account information from innocent computer users,'' says Cluley. ''All Internet users need to ensure their computers are properly defended with the latest up-to-date protection software, and make sure they are not putting themselves in jeopardy.''

Key-loggers are able to track specific information such as passwords, account numbers and user names. Trojans and worms lurk in the background on PCs, spying on everything that occurs on the computer -- including secretly capturing every keypress -- and sending that information over the Internet to criminal hacking gangs.

Sophos analysts report seeing a three-fold increase in the number of key-logging Trojans roaming the Wild.

''Over the last year, we have seen a dramatic rise in the number of new viruses, worms and Trojan horses designed to steal the keystrokes of innocent computer users,'' says Graham Cluley, senior technology consultant for Sophos. ''Sophos's labs produce protection against approximately 15 new pieces of malware, which include this sinister payload every day, compared to 5 a day a year ago.''

The British banking industry has published information about how online bank customers can take steps to stay safe online at this site.