Rail services replaced by buses between Cambridge and Ipswich
A fault with the signalling system between Elmswell and Bury St Edmunds means all lines are currently blocked.
Buses are replacing trains on the Ipswich to Cambridge route.
Disruption is expected until 3.30pm.
A Network rail team is expected on site at 1.45pm and will have the problem resolved as soon as possible
Abellio Greater Anglia apologised for the disruption caused.