The issue appeared to be linked to BT's DNS servers, which help route traffic on the internet. However, BT says it's "caused by power issues at one of our internet connection partners' sites in London." It's believed a power outage at London data centre TeleCity is to blame. "We're sorry that some BT and Plusnet customers have been experiencing problems accessing some internet services this morning," says BT. "Services are now being restored, and engineers are working to fix the problems for the remaining customers that are affected."

Some users have reported that if you change your DNS server to Google's Public DNS addresses (8.8.8.8 and 8.8.4.4), you might be able to get back online. VPN connections may also work too.

Update - 1pm: BT says things should now be returning to normal: "We're sorry that some BT and Plusnet customers experienced problems accessing some internet services this morning. Around 10 per cent of customers' internet usage was affected following power issues at one of our internet connection partners' sites in London. The issue has now been fixed and services have been restored."

