A former Flying Squad commander has told Sky News he believes the multi-million pound raid on safety deposit boxes in London's diamond centre was carried out with the aid of accomplices on the inside.

John O'Connor said he could not believe how easily raiders gained access to the building in Hatton Garden sometime over the Easter weekend.

Police have revealed the thieves disabled a lift and climbed down the lift shaft into the basement, but there was no sign of forced entry anywhere in the building, which the safe deposit company is only part of.

They then used power tools to drill through a two-metre thick wall.

Up to 70 safe deposit boxes inside Hatton Garden Safe Deposit Ltd were then broken open, with victims still being informed.

Mr O'Connor told Sky News: "You've got a major strong room, there's no sign of a forced entry, they've apparently been able to abseil down the lift shaft to get access to the vault - I just find it astonishing that it was that easy.

"The fact that there is no sign of forced entry, what does that mean? That someone left the door open? That someone left the windows open?

"It smacks all the time of inside aid, all of the way through it. This doesn't look to me like a genuine sort of smash and grab raid by determined criminals, this looks like they've had accomplices on the inside.

"You wouldn't go to attack a building like that unless you knew you could gain access."

On Thursday, police said the "sophisticated" raid could only have been carried out by a limited pool of people.

Detective Chief Inspector Paul Johnson, of the Flying Squad, said those behind the heist had left a "chaotic scene" in their wake.

He said: "It's organised, it's sophisticated, it's people who have planned it and they know how they're going to go about and commit this crime.

"So I would imagine that pool of people is quite limited."

He added that the thieves had left numerous power tools inside the vault and said an alarm had been triggered, although he did not confirm when this took place.

Reports have claimed the alarm on the building was activated last Friday. The theft was discovered on Tuesday morning.

Police are in the process of identifying the owners of the safe deposit boxes.

Mr Johnson added: "This is a slow and ongoing process. We are still forensically examining the scene for evidence as we go through this process.

"This is painstaking and it is slow but essential to make sure that we are maximising the amount of evidence we capture at this stage, and any opportunities we can give ourselves later to identify who the thieves are."