Trains between London and Norwich are being cancelled this morning as a result of engineering work not having been completed on time
Replacement buses are already in operation between Newbury Park and Ingatestone for engineering work as planned this weekend.
However rail operator Greater Anglia has now confirmed that engineering work between Diss and Norwich has not been completed on time, meaning all lines are blocked.
It means that all London-Norwich and Norwich-London trains are being cancelled until at least midday.
No details of any replacement bus service have been given.
However, hourly London trains starting or finishing at Ipswich are still running to and from Ingatestone, with a bus replacement running between Ingatestone and Newbury Park.
London Underground central line trains run to and from Newbury Park to the centre of London, including Liverpool Street.
A spokesman from Greater Anglia said: 'Due to engineering works not being finished on time between Norwich and Diss all lines are blocked.
'Train services running to and from these stations will be cancelled. Disruption is expected until 12:00 21/01.
'We apologise for the disruption to your train services this morning.'
The following trains have been cancelled as a result of the work:
07.00 Norwich to Shenfield
08.00 Norwich to Shenfield
09.00 Norwich to Shenfield
09.35 Shenfield to Norwich
10.00 Norwich to Shenfield
10.35 Shenfield to Norwich
11.35 Shenfield to Norwich
12.35 Shenfield to Norwich
Passengers at Norwich are being advised to use the Great Northern services between Cambridge and London King's Cross, where Greater Anglia tickets are being accepted, with services running from Norwich to Cambridge.
Other than the London services starting or ending at Ipswich, which are still running, the only other alternative for Suffolk passengers is to travel to Cambridge, before then travelling via Great Northern to King's Cross.
A statement from Greater Anglia said: 'Great Northern are conveying passengers between Cambridge and London Kings Cross in both directions until further notice.
'Arrangements have been made for Greater Anglia rail tickets to be accepted for these journeys.
'Customers at Norwich can use valid Greater Anglia tickets to travel on Greater Anglia services between Norwich and Cambridge, and tickets will then also be valid on Great Northern services between Cambridge and London King's Cross.'
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