MINERS are working in “Saharan temperatures” in a 24-hour-a-day effort to produce salt to melt the region’s frozen roads, a union says.

Workers at Cleveland Potash in Loftus, east Cleveland, are travelling to Boulby mine in sub-zero temperatures and then digging vital supplies of salt more than a mile underground in temperatures of up to 43C, Unite says.

Councils across the region have relied on the mine to replace their stocks, which have been ravaged by the appalling weather conditions.

Union officials praised the workforce, stating that many had sacrificed much of their Christmas break to step up salt supplies.

John Chilton, a local Unite official, said: “Unite members at Britain’s biggest salt mine are travelling to work in Arctic weather but working flat out in Saharan temperatures to mine the salt which keeps Britain’s roads and pavements safe.”

Almost all the grit used in England comes from Boulby mine and Winsford Rock salt mine in Cheshire.

Dave McLuckie, external affairs officer at Cleveland Potash, said salt was being mined on a 24-hour basis.

“Over this weekend, about 13,000 tonnes of salt has left the Boulby mine, that’s equivalent to about 650 lorries,” he added.

“It has been moved by a number of means including direct loading onto gritting vehicles, lorries and by trains from the mine to Tees Dock for onward shipment by vessel to various parts of the country.”

Mayor of Middlesbrough, Ray Mallon, said the council had a stockpile of 400 tonnes of road grit with more than 100 tonnes arriving daily from Boulby potash mine.

Durham and North Yorkshire county councils said low salt stocks meant gritting was being restricted to “priority routes”.

A spokesman said: “In North Yorkshire, we made sure that all of our salt barns were filled at the start of the winter and our stock levels were about three times the level being recommended for local authorities to hold.

“Even so, the continued use of salt in keeping our roads open has meant that we have a difficult situation to manage.

“We must be prudent in our salt use in order to conserve stocks.

“Routine salting is being restricted to the priority gritting routes, which accords with the practice being directed nationally.”

A spokesman for Durham County Council said that due to current under supply and future uncertainty regarding the supply of salt, it was necessary to prioritise gritting to all A roads and B roads throughout the county “The council will continue to keep the situation under review and as soon as more salt becomes available we will reprioritise,” he said.