Council bosses have been hit with yet another embarrassing problem with Norwich roadworks, with part of a £150,000 scheme having to be redone because a mystery problem caused paving slabs to crack.

After issues in Tombland, The Avenues, Hall Road and Cattle Market Street, the latest Transport for Norwich project where problems have arisen is in Colegate.

The road was shut at the junction with St Georges Street in March for nine weeks for a £150,000 project, which included putting in a raised table, kerb realignment and footway widening.

But some of the paving slabs which were put down have cracked, with council bosses and contractors Tarmac unclear just what the cause is.

Work to replace the damaged paving started on Monday, November 7 and was meant to be completed by Friday. But, Tarmac said 'adverse weather conditions' meant it would now not finish until today – a day after all roadworks around Norwich were supposed to be suspended in the run-up to Christmas.

And even when the current work is finished, which Tarmac says will mean two thirds of the repairs will be complete, it will have to return to finish the final third in the spring.

A spokeswoman for Transport for Norwich said: 'We are obviously disappointed that there is an issue with the paving at the St George's Street/Colegate junction.

'Tarmac has responded promptly and the necessary repair work is being carried out with as little disruption as possible. We are looking into the cause and monitoring progress carefully.'

A spokeswoman for Tarmac said: 'We are undertaking works to replace damaged paving at the St George's/Colegate Junction.

'Local businesses and residents are being kept informed and we apologise for any inconvenience caused while the works are undertaken with as little disruption as possible.'

Investigations are continuing to establish what went wrong. It is not yet clear what the cost of the repairs will be or who will shoulder the bill for it, although Tarmac says it is not connected to the problems with asphalt it used on other schemes.

Businesses have expressed their disbelief at the length of some of the projects.

Anne Duarte of St George's Music Shop said: 'It should have been finished six months ago. They are still 'revamping' a junction that should have been completed a year ago. It's the third time they have attempted this in not too many months. It is outrageous.

'The costs are just ridiculous. They should have done it properly the first time.'

Andy Cooper, of the Playhouse, said he welcomed the changes as a cyclist.

'It's embarrassing that it has taken so long,' he added. 'But it is a job that needs doing and it is good that the council are attempting to see it through, even if it is going to take a lot longer.

'Hopefully when the spring comes they will have better conditions to complete the work in. I don't feel they should force the work through too quickly because more problems will just arise.'