New figures have revealed a massive rise in bank customers hit by an email scam.
MessageLabs, which monitors spam messages sent to its customers, said it had stopped 337,350 "phishing" emails in January, compared with just 279 last September.
And a spokeswoman warned this only represented the "tip of the iceberg" for the scam.
Phishing involves sending out millions of emails to people directing them to a website masquerading as their bank's own online home.
But the site is a carbon copy of the original set up by sophisticated criminal gangs who hope online customers will be prompted to disclose names, account details and passwords.
The information is then used by the gang, who go to the bank's real website to clean out the customer's account.
March's figure for the number of messages intercepted by MessageLabs on behalf of its 8,500 business customers dropped to 215,643.
But information security analyst Natasha Staley said the total number of emails being sent to UK computer users would be far higher.
She said: "We are only monitoring our customers' emails so this is just the tip of the iceberg.
"The true extent of the problem is just impossible to quantify."
MessageLabs, which monitors spam messages sent to its customers, said it had stopped 337,350 "phishing" emails in January, compared with just 279 last September.
And a spokeswoman warned this only represented the "tip of the iceberg" for the scam.
Phishing involves sending out millions of emails to people directing them to a website masquerading as their bank's own online home.
But the site is a carbon copy of the original set up by sophisticated criminal gangs who hope online customers will be prompted to disclose names, account details and passwords.
The information is then used by the gang, who go to the bank's real website to clean out the customer's account.
March's figure for the number of messages intercepted by MessageLabs on behalf of its 8,500 business customers dropped to 215,643.
But information security analyst Natasha Staley said the total number of emails being sent to UK computer users would be far higher.
She said: "We are only monitoring our customers' emails so this is just the tip of the iceberg.
"The true extent of the problem is just impossible to quantify."
