BT broadband customers across the UK have been hit by a major outage, after the company experienced a power failure at an exchange in Birmingham.

The problem has affected customers in cities such as London, Belfast and Edinburgh, according to the BBC.

BT said in a statement that its engineers were “on-site” and that the majority of customers now had connectivity again. “We are working to restore service to remaining customers as soon as possible this afternoon.” It advised customers still unable to access the internet to restart their modems.

The problem prompted angry comments from businesses and consumers on Twitter. Comedian Richard Herring wrote: “BT confirmed massive broadband outage causing problems for most of their customers. Sounds like business as usual.”

Another person commenting, 'Machlight1', wrote: “BT can't cope with No. of calls & suggest via a recorded message that you check online. Genius.”

As of 3pm, BT had fixed problems in areas including Birmingham, Chester, and Surrey. But issues remained in counties including Kent and Northamptonshire, and in parts of London’s East End.