There were prospects of a respite for councils facing a grit shortage as the freezing weather continued.

A fleet of lorries began delivering the first supplies of 12,000 extra tonnes of de-icing salt made available by chemicals firm Ineos.

The first 50 trucks have left the firm's depot in Runcorn, Cheshire, with another 50 scheduled to deliver more supplies on Monday.

The salt will be supplied to some of the worst-hit areas including Pembrokeshire in Wales, East Yorkshire, Fife, Gloucestershire, Bradford and Sheffield.

All of the 12,000 tonnes was destined to be delivered to Wilhelmshaven in Germany for use in producing chlorine and some foodstuffs. But given the weather and emergency requests from local authorities, the load was diverted for use in the UK.

"Ineos is aware of the salt shortages in the UK and the problems this is causing," said Harry Deans, CEO of the firm. "12,000 tonnes of road salt will not solve the problem but it should make a difference in the places most severely affected."

Meanwhile Transport Secretary Lord Adonis defended rationing of grit supplies, saying it would help keep the major road network open.

Emergency measures have been put in place to reduce the 60,000 tonnes used each day by councils across the country, with local authorities forced to cut their use of grit salt by a quarter, and the Highways Agency has decided not to grit the hard shoulder of motorways.

Lord Adonis said on Sky News Sunday Live: "The forecasts are for nine consecutive nights of sub-zero temperatures coming up. That being the case, we would have been acting irresponsibly and local councils would have been acting irresponsibly if they did not plan properly.

"By taking this step together we will ensure those supplies of grit we have got will continue, and we will be able to keep most of the major roads open."