Potentially millions of customers are still unable to access their HSBC accounts online, with the service outage now in its second day.

As The Register reported yesterday, the problems occurred at 8am Monday (4 January). The bank has ruled out a DDoS attack as the cause, but has not elaborated further.

Business Banking services are currently running at a significantly reduced capacity and running slower than normal, said the bank in a statement this morning.

It advised customers with pressing need to make urgent payments to use its business telephone service instead.

It said: "Online services are not currently working but customers can access the Personal Banking Mobile app. Due to high demand the service may be slow. We continue to work on a fix for online services."

A spokeswoman for the bank said: “We apologise for any inconvenience this may have caused and our teams continue to work non-stop to restore all services. Regular updates will be provided.

“We will ensure customers do not lose out as a result of this issue.”

The last major IT glitch HSBC encountered was in August, when a cock-up with the Bankers' Automated Clearing Services (BACS) payment system left 275,000 HSBC account-holders without their pay cheques.®