Villagers in Bacton are no closer to discovering what caused an explosion at the area's gas terminal 15 months ago after investigators revealed there was no end in sight for their inquiry.

Villagers in Bacton are no closer to discovering what caused an explosion at the area's gas terminal 15 months ago after investigators revealed there was no end in sight for their inquiry.

The blast, which happened in February 2008, shook houses in the area surrounding the Shell operated terminal and left a column of black smoke towering into the sky.

An investigation into the cause of the explosion was immediately launched by the Health and Safety Executive and the Environment Agency but 15 months on they have still not released their findings.

In March, the investigators said they hoped to have completed the inquiry by late spring or early summer after concerns were raised that villagers had been left in the dark not knowing why it had happened or how serious it was.

But in a statement released this weekend, it was revealed interviews were still being carried out.

A spokesman for the HSE and Environment Agency said: ''We cannot give an estimate as to when the investigation will be complete but can assure people that we are all working hard to conclude enquiries.

'It is important that investigations of this kind are thoroughly conducted to ensure that successful enforcement action can be taken if and as required.'

North Norfolk MP Norman Lamb, who has previously spoken out about the delay, said he thought it was 'extraordinary' that villagers were still being denied peace of mind.

He said: 'I find it hard to imagine why it needs to have taken this long. Is there some issue that is causing enormous concern?'

The MP said he would be contacting the investigating authorities to ask them to justify the long delay in releasing their findings.

The Environment Agency and HSE said it had specialist staff working full time on the investigation which it described as 'highly technical and complex'.

A spokesman said investigations had been known to take years but added: 'Since the incident we have worked with Shell to help them improve their performance in terms of their management of the facility.'

Shell, which owns part of the site, has already carried out its own internal investigation but is awaiting the completion of the government inquiry before it releases its findings.