The horrific crash on the M5 which has killed seven people has triggered a renewed debate on whether the speed limit on the UK's motorways should be raised to 80mph.

In September the government launched a consultation on raising the maximum speed limit from its current threshold of 70mph, which was set more than fifty years ago.

At the time the government said it wanted to "put Britain back in the fast lane of global economies, and look again at the motorway speed limit which is nearly 50 years old, and out of date thanks to huge advances in safety and motoring technology."

However since the crash on the M5 on Friday night road safety charities including the Royal Society for the Protection of Accidents have said the government's plans should be abandoned.

Tory MP Margot James told Jeremy Vine on BBC One there shouldn't be a rush to judgement on the speed limit, saying: "We don't know fast people were driving. I don't think people were driving that fast anyway, from the reports I've heard from the people interviewed who survived the accident. So I'm not sure it was the speed that was causing the problem. The fog was obviously a problem, but we don't know yet."

The Transport Secretary Justine Greening has said the government will also investigate the causes of the pile-up, which involved 34 vehicles and in which at least seven people are known to have died.

"Some people have said that the weather was particularly bad, but I think clearly what we need to do at the moment is focus on the NHS work that's happening to take care of the people who have been injured, but also getting the motorway back open again for the public as soon as possible. I think we'll have a debate about the policy issues in the coming weeks."