Trains running through Peterborough have been cancelled due a fault in the electricity supply between Newark North Gate and Grantham.
This is affecting trains on the East Coast Main Line which runs between London and Edinburgh, taking in Peterborough.
LNER which runs the line said trains may be delayed by up to 70 minutes, cancelled or revised.
It has already announced that a number of services have been cancelled.
Disruption is expected to continue until 4.30pm.