Train lines blocked due to signalling system fault between Sunderland and Billingham

Some train lines have been left blocked due to a signalling system fault.
A Northern train.A Northern train.
A Northern train.

Rail provider Northern says that some lines between Sunderland and Billingham stations have been left blocked due to the problem.

Services running through the stations may be cancelled or delayed for up to 45 minutes.

Disruption is expected until at least 2.15pm.