Halifax has become the latest target for an e-mail scam tricking customers into giving away confidential bank details, BBC News Online has learned.
The bank closed its online facility after customers received e-mails asking them to click on a website link and reveal their security details.
The scam has also targeted Barclays, Lloyds TSB and NatWest customers in the past two months.
A Halifax spokesman said customers would be compensated for any losses.
Phishing scams are becoming a growing problems
And the bank would impose additional security measures before the facility reopens, to prevent fraudsters gaining access.
The spokesman also told BBC News Online anyone who feels they may have been affected should contact Halifax immediately.
The scam, known as "phishing" has also hit large retail banks in the US, Australia, New Zealand and mainland Europe in the past year.
Cap Gemini security expert Jon Colombo told BBC News Online: "Banks should make sure they have a decent response policy in place as this will limit the damage to the brand that will occur."
"Once it starts, it is very hard to stop".
"Phishing" is only the initial stage of a two-tier scam originating in Eastern Europe.
The second stage, known as "money transfer" or "job offer scam", involves advertising for British people with UK-based accounts to act as agents to transfer money overseas.
Barclays told BBC News Online a number of its customers had fallen for this "job offer" scam.
Anyone who has concerns can contact Halifax's helpdesk on: 0845 6020000.