“It is certainly not good that such a serious breakdown can occur, leaving customers without the service for such a long period of time,” said senior risk expert Agnieszka Arshamian at to Swedish business daily Dagens Industri (DI) on Wednesday.

Swedish bank Skandiabanken’s internet service was down for most of Tuesday, leaving thousands of customers unable to pay bills, move funds or manage their stock portfolios.

Webpages, internet banking, as well as telephone and customer services were all unavailable for several hours and internal e-mail and intranet were down as well.

Not until midnight on Tuesday were all systems up and running again.

“This is the most serious breakdown in the history of Skandia, we are deeply sorry for any problems we may have caused our customers,” said Pelle Wahlström, chief operating officer, in a statement on Wednesday.

Skandiabanken reported the incident to FI who will now investigate if the bank had the necessary precautionary arrangements to minimise the risk to customers.

According to Arshamian this kind of breakdown does not happen often in Sweden.

She said that FI would follow up on the incident carefully. If there is reason to believe that the incident wasn’t handled appropriately the bank may face stern criticism.

“There must be efficient risk management so that problems are prevented, as well as an effective crisis management if they do occur. When you are the most dependent on IT-systems your vulnerability is increased,” she said to DI.

Skandiabanken has more than 350,000 customers in Sweden and an estimated 1.7 million customers worldwide.