Investigations into why Great Yarmouth's unexploded bomb was missed during earlier survey work are now underway.

Last Tuesday, a 250kg bomb - believed to be from the Second World War - was reported to police during dredging work close to the town's third river crossing development.

Police were called to the scene at 11.36am, and a 400-metre cordon was put in place in the area.

Great Yarmouth Mercury: Members of the Explosive Ordnance Disposal team at work by the unexploded bomb in Great Yarmouth.Members of the Explosive Ordnance Disposal team at work by the unexploded bomb in Great Yarmouth. (Image: Denise Bradley)

Over the following four days, military personnel with the Explosive Ordnance Disposal team worked with Norfolk Constabulary to defuse the bomb while protecting nearby residents, homes and infrastructure. A 400-tonne sand blast barrier was built around the device.

The bomb detonated on Friday just before 5pm, during slow burn work to disarm the explosive.

Before construction began at the third river crossing site, Norfolk County Council carried out surveys on unexploded ordnance (UXO) in the area.

Investigations are now underway to assess why the unexploded bomb was not identified during the earlier stages of the bridge's construction.

Great Yarmouth Mercury: The bomb exploding in Great Yarmouth on Friday.The bomb exploding in Great Yarmouth on Friday. (Image: Video shared by Casey Goodrum)

As well as confirming the investigation, the county council says it is assessing the impact the massive blast had on the third river crossing construction project.

Tim Ellis, Norfolk County Council's project manager overseeing the construction of the crossing said: "The highway works and main bridge construction are all above ground, and we do not presently believe they will be significantly impacted. But further works on the quay wall will be delayed until further assessments have been completed.

"We are unsure at present how long this process will take or what impact it will have on the project’s overall budget and timeline but will provide further information once we’ve had sufficient time to review the details with the contractor."

Mr Ellis said the third river crossing is still expected to be complete by this summer.

Great Yarmouth Mercury: The third river crossing in Great Yarmouth is expected to open in summer 2023.The third river crossing in Great Yarmouth is expected to open in summer 2023. (Image: Norfolk County Council)

Following the bomb's detonation, all army and emergency service workers were accounted for, and no injuries were reported in the area.