All lines between Norwich and Lowestoft are blocked following a swing bridge failure.
Reedham swing bridge has failed, meaning trains are unable to use it and travel between Cantley and Haddiscoe.
Trains between Lowestoft and Norwich are likely to be cancelled or diverted,, with disruption likely to last until 6pm.
Greater Anglia's website said: 'Due to a fault with a river swing bridge between Haddiscoe and Cantley all lines are blocked. Network Rail engineers are en route to the area.
'Train services running through these stations may be cancelled, delayed or revised. Disruption is expected until 6pm today.'
This problem adds to the issues facing visitors to Lowestoft this weekend, with planned engineering work overnight between Saturday, September 22 and Monday, September 24, meaning bus replacement services will be serving the routes between Norwich and Lowestoft on Sunday, September 23.
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