Commuters are being told to expect “major delays” between Waterloo and Wimbledon throughout the entire day.
The South West Trains services are being taken down by a signalling problem between Wimbledon and Earlsfield, affecting a number of lines into the main London terminus.
Lines between Waterloo and Wimbledon were closed, but have since been reopened. However this caused delays of up to 60 minutes throughout rushour.
Initially National Rail said services were expected to return to normal by 10am, but this has now been extended to 4pm
Commuters are being advised to seek alternative routes including using First Great Western, Southern or Thameslink mainline trains as well as London buses or the Tube.
The disruption, which has been exacerbated by problems with the District Line, is already causing headaches for many passengers.