While users were able to access major sites such as bbc.co.uk and the Telegraph, others including Twitter, Amazon and even BT’s own service status pages were inaccessible to users across the UK.
The affected sites remained available to users of other ISPs and via 3G and 4G, confirming that the issue was within BT’s network.
BT says engineers have now resolved the issue and has apologised to customers “for any trouble caused” by the outage.