Troops will begin training to help deliver petrol supplies as Boris Johnson said he was making preparations to deal with potential problems until “Christmas and beyond”.

The Prime Minister said the situation on the filling station forecourts is “stabilising” as he urged motorists to go about their business in the normal way.

A decision to put 150 military drivers on standby has been formally approved, meaning they can begin training in case they are required.

A further 150 drivers’ mates are also ready to help out as part of the military effort.

“They’re still on standby but can now start training now it’s approved,” a Government source said.

They will be held in a “state of readiness” and could deployed “in the coming days” if needed, sources said.

Officials from the business department and the Ministry of Defence are working with the petrol industry on where the drivers will be best placed to support.

On Tuesday Mr Johnson tried to calm nerves about the supply chain problems affecting businesses across the country.

“We now are starting to see the situation improve, we’re hearing from industry that supply is coming back onto the forecourt in the normal way.

“And I would just really urge everybody to just go about their business in the normal way and fill up in the normal way when you really need it and you know, things will start to improve.

“What we want to do is make sure that we have all the preparations necessary to get through to Christmas and beyond, not just in the supply in the petrol stations, but all parts of our supply chain.”

Following days of chaos, with long queues for petrol and stations running dry, the Prime Minister said he understood the frustration felt by drivers as they struggled to fill up.

The head of a fuel supplier has predicted the UK is over the worst of the shortage at petrol pumps.

James Spencer, managing director at Portland Fuel, told the BBC: “I would say logically the worst is behind us. The original crisis – if you want to call it that – was caused by 25 to 30 petrol stations closing down near the south coast.

“It was never a particularly major crisis in the first place, obviously then there was the panic buying, sales at forecourts went up by 500% over the weekend.

“Lot of people have filled up their tanks now, so you might actually see a dip in demand and the replenishment of fuel at petrol stations is a 24-hour, seven-days-a-week job, so as we speak the petrol stations are being replenished.

“To a certain extent that hasn’t been helped by all the queues at the petrol stations because all of the tankers have not been able to get in.”