Customers of HSBC were unable to access online banking for a period of time this morning due to an IT-related failure.

Customers vented their frustrations on Twitter on Friday, complaining that they are unable to access their online and mobile banking accounts. Laura Harper (@LauraJHarper24) tweeted: "@HSBC_UK_Help please can you sort out your online business banking. Going very slow this morning & I have people waiting to be paid!"

Dan Roach (@Danroachlfc33) said: "@HSBC_UK_Help can't log on to the HSBC website. Really slow & nothing happens. What's the problem?"

The bank apologised to customers via its Twitter account, promising to bring the service back online as soon as possible.

A tweet from the bank read: "We apologise to anyone experiencing problems using internet banking. Our IT teams are aware of the issue and working to restore the service."

An HSBC spokesperson told ComputerworldUK that the service is now back up and running following the outage which began at around 9am, lasting for just over an hour. The service is likely to be slower than usual due to higher traffic as the service resumes normality, due to a backlog of internet banking customers attempting to access their accounts.

The spokesperson confirmed that the outage affected only personal and business accounts in the UK, with ATMs, call centres and other infrastructure continuing to function as normal.

The outage is said to have been the result of an "internal server issue", though no further details of the ouatge were available at this point.

The HSBC outage is the second IT failure this week to affect major banks. Earlier this week a data centre fault resulted in an online banking outage which marred the re-launch of TSB, with Lloyds customers also affected.