Didcot power station recovery work could take 'many months'

"It will take many weeks and, in reality, many months before we will be able to get access to those trapped," he said.

"This is a complex process and will take some time."

The building collapsed at 4pm last Tuesday while workers were preparing it for demolition, killing worker Mike Collings and trapping three others inside the rubble.

Five people were injured and more than 47 others were treated for dust inhalation.

Emergency services and rescue workers have said it is "highly unlikely" that those trapped will be found alive.

The exact cause of the collapse is still unknown and Thames Valley Police and the Health and Safety Executive are working to identify the cause as rescue teams comb through the rubble pile, which is about 30ft high.

Peter Baker, the chief inspector of construction at the Health and Safety Executive (HSE), said they are conducting the joint investigation with the police under the work-related deaths protocol.

He said: "Everyone is working very hard to identify the causes as quickly as possible, and also to see what lessons can be learnt to make sure we can avoid a tragedy such as this in future."

Mr Baker said the HSE have assembled a specialist team with construction and demolition

experience and that they will remain on site to "ensure that the health and safety risks" from the next phase of the power station demolition are "being effectively controlled".

Mr Chilton said the recovery of the bodies will be a "complex and difficult engineering operation" - and that as of yet it has not been "appropriate or safe" to dismantle any of the wreckage.

He added: "What is incredibly important is that the family are kept up to date with the progress of the investigation and the specialist techniques we are using to try and get access to the persons that are trapped."

So far the operation to try and locate the missing individuals has involved the use of sniffer dogs, listening devices and drones, and emergency services were considering deploying remote control probes to access the dangerous parts of the site.

Mr Chilton said that the purpose of the drones and robots was to see if it was safe to get access and to take pictures for the specialists to use when making an informed view of how they would get to those trapped.

He told reporters at the scene that they have been taking statements from workers who witnessed the collapse to try and figure out where the missing were.

Paying tribute to the families affected, Mr Chilton said: "This is an incredibly difficult time for them, they have suffered a tremendous loss and it will take some time for them to receive closure on this.

"I would like to thank them for their sensitivity, understanding and patience for the traumatic events that happened last week."