The Northern line tweeted: “No service between Charing Cross and Kennington southbound only due to signal failure at Kennington. Severe delays on the rest of the line.”

The severe delays on the popular tube line have left commuters using local buses, which according to Twitter users are "crammed". 

The tube line is urging people to use alternative transport and tickets are valid on local buses and Thameslink. 

Twitter user Joanna Morgan said: “Oh of course, the one day I need to use the Northern Line, there are severe delays.”

Coleen Mensa said: “Northern line suspensions is really trying to throw my morning into disarray”. 

Lucy Parts tweeted: “Buses are rammed and Tooting Bec weren’t letting people in when I came out.”

Some Twitter users said they tried to use the taxi company Uber to get to their destination, but their fares had increased substantially because of the signal failure on the Northern Line. 

Commuters have complained on Twitter of being left sitting at stations and not moving. 

Sam Jones tweeted: “An hour and a half to get through nine stops on the tube, and paying £4 for the privilege. Thanks Northern Line.” 

There are about 252 million passengers journeys on the Northern line, making is the second-busiest on the Underground.