Train travellers between Norwich and London have been affected by delays and cancellations due to a points failure.
Greater Anglia said the problem at Manningtree meant trains were having to run at reduced speed on the line towards Colchester.
They said passengers would face cancellations of train services or delays of up to 30 minutes, with disruption expected to continue until 8.30am.
The 6.45am Norwich to London Liverpool Street service and the 9am from Liverpool Street to Norwich have both been cancelled, while the 4.55am and 5.25am services from Norwich to Liverpool Street were hit by delays.
Network Rail engineers are working to fix the problem.
And problems with level crossing barriers and a tree blocking the line at Wymondham have been causing delays to services between Norwich and Cambridge.
The 7.04am Cambridge to Norwich and 7.37am Norwich to Cambridge services are among those affected by delays, while the 8.40am Norwich to Cambridge train was cancelled.
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