Merchants are calling for compensation from HSBC, after its Secure e-Payments system left them unable to take payments earlier this week, in its third reported outage this year.

The credit card payments system stopped working at 5pm on Monday and was restored on Tuesday evening, according to reports. It also went down during a weekend over the weekend of 29-30 March, and one day in January, the reports said.

The bank has confirmed the system is now working, but did not provide immediate further comment on the reasons for the outage. According to retailer comments on an HSBC user forum, HSBC experienced database problems.

Retailers wrote on web message boards, expressing anger at lost revenues as a result of the system outage. On Actinic Community, a message forum for users of that e-commerce system, user Dex said it had been difficult to get an update from the bank.

On the problems in March, user Adrian Higgins wrote: "It was bad enough in January when it was down for 24 hours. Got up this morning.... still down. Just phoned HSBC and got through all they say is that their IT department are working on it!!! I must admit we use two payment gateways HSBC and Paypal - I think it is time to get a third!"

Timmo wrote: "I think HSBC is too unreliable, I know that I have over £2,000 of sales waiting to be processed from yesterday and I know that I lost a lot more."

On the UK Business Forums website, numerous users were calling for compensation from HSBC.

This latest trouble for the bank follows news that HSBC admitted it had lost 370,000 customer details after an unencrypted, password-protected computer disc went missing in the post.

The bank has invested heavily in IT in recent years to run online banking and transactional services.

Retailers use the online system to process card payments quickly. They can either provide a link to an HSBC hosted payment page, or build their own front end that links invisibly into HSBC's payment processing technology.

It links into Verified by Visa and MasterCard SecureCode transaction security systems, and can process transactions from shopping basket systems such as Actinic, Adelante, BT Openworld Internet Trader, Shopcreator, Intershop, Oscommerce, e-Pages and Clickcart Pro.