Signalling problems at Eaglescliffe causing delays of up to 30 minutes on First Transpennine Express between Northallerton and Middlesbrough.
Also causing delays of up to 30 minutes on Grand Central Trains between Northallerton and Sunderland, and on Northern Rail between Darlington and Saltburn.
There is currently no estimate for when a normal service will resume.
More top news
Emma Jesson brings you Saturday night's forecast
Feeling much colder later on Saturday. Wintry showers possible on Sunday and Monday
The pressure group Ashley Out has called for demonstrations outside every Sports Direct store within a 20-mile radius of St James' Park.