Severe rail delays triggered by over-running £7m engineering works have been blasted as 'totally unacceptable' by a Norwich MP.

Eastern Daily Press: Major disruption on the trains caused travel chaos from Ipswich.Major disruption on the trains caused travel chaos from Ipswich. (Image: Sarah Lucy brown)

And rail bosses have apologised after thousands of train passengers were hit by delays, pledging a 'full review' into what went wrong.

Greater Anglia advised passengers not to travel unless their journey was 'essential' yesterday morning, and commuters fear weeks of misery – with track upgrade work planned every weekend until July 6.

Rail users had faced a muddle of alterations and cancellations until midday yesterday, with services delayed by up to two hours.

The improvements around Colchester station aim to create more reliable services for the growing number of passengers on the Norwich to London line.

While Network Rail bosses blamed delays on 'technical problems' and apologised, Norwich North MP Chloe Smith said it was not good enough.

'It's totally unacceptable to have over-runs like this,' she added. 'It really affects people's working lives, and travellers as well as commuters.

'I will be speaking to Network Rail to put across how much people require that service and how strongly they feel about disruption on this scale.'

She added a 'full explanation' was needed and said it must not be allowed to happen again.

'As part of my work on the Norwich in 90 taskforce [which aims to cut the Norwich to London journey time to 90 minutes] I will be looking to understand any long-term improvements that are required to make sure our line is more resilient and gets people where they need to be on time,' she said.

The first service able to pass through Colchester was the 8am Norwich to London train.

Jamie Burles, managing director of rail operator Abellio Greater Anglia, and Richard Schofield, managing director of Network Rail, issued a joint apology for the disruption.

They said: 'We would like to sincerely apologise to all of our customers who were affected by the disruption to services in the Colchester area and for the frustration and inconvenience this caused.

'The track replacement work was not completed on time because of problems that were encountered during the excavation and subsequent reinstatement of the track and with the on-site machinery. A full review is under way to understand how these problems could have been avoided, as part of our determination to avoid any repetition of the difficulties that affected services.

'Subsequent alterations to services were necessary in recovering the scheduled timetable, and we made every effort to restore the normal service as soon as we could.'

Ticket restrictions were lifted and customers who had tickets for travel yesterday may use them today.

Customers delayed by 30 minutes or more are entitled to claim compensation. Forms are available from staffed stations or information can be obtained from www.abelliogreateranglia.co.uk