Cars were pulling up pieces of some roads after they melted

In Cornwall, workmen from the county council had to cover the B3359 at East Taphouse with protective dust on Tuesday to prevent further damage.

Roads around Stithians are also being covered with sand and grit to help keep them open to motorists.

In Devon, the B3232 between Torrington and Huntshaw Cross was closed. Traffic is being diverted onto adjacent routes.

Ermington Road in Ivybridge is also under review and being treated with crushed rock.

Warning signs

Cornwall County Council urged people to keep speeds down and said preventative work was the key. Anyone who sees similar problems is asked to contact local highways bosses.

Problems started on some roads when bitumen that held stone chippings forming the road's surface in place became soft. It began sticking to car tyres, which then pulled up small pieces of road.

Andy James, from Cornwall County Council, said the substances being spread on the roads should prevent the problem getting worse.

He said: "It helps to absorb the excess bitumen and prevent it from sticking to tyres as they pass over.