A Greater Anglia train. Picture: Sonya Duncan (Image: ARCHANT EASTERN DAILY PRESS (01603) 772434)
Rail passengers travelling between Norwich and Cambridge are facing delays and possible cancellations to services.
Problems are being caused by a fault with barriers at a level crossing in Brandon.
All lines through the area have subsequently become blocked.
Greater Anglia said disruption is expected to continue until 1pm.
A spokesman said: 'The level crossing barriers are defective at Brandon due to the nature of the fault trains are currently unable to proceed in either direction through Brandon station.
'Train services between Norwich and Cambridge may be cancelled, delayed by up to 40 minutes or revised.'
They added: 'Network rail staff are due on site to ascertain the nature of the fault.'
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