Train services between Norwich and Lowestoft and Norwich to Great Yarmouth are being disrupted due to level crossing problems.
Trains are having to run at reduced speeds "on all lines" which is causing some delays, according to Greater Anglia.
A statement on the Greater Anglia website said: "Due to a problem at a level crossing between Norwich and Lowestoft and between Norwich and Great Yarmouth trains have to run at reduced speed on all lines.
"Train services running to and from these stations may be cancelled, delayed or revised. Disruption is expected until 10am on February 27."
The problems have been found "at multiple level crossings between Norwich and Reedham", with Network Rail engineers on route to the affected areas.
It adds: "Greater Anglia and Network Rail are sorry if your journey has been affected by this disruption."
To keep up to date with train service alterations visit www.journeycheck.com/greateranglia/
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