The M25 was closed at Potters Bar overnight after the carriageway “buckled” and created a ridge in the road surface.

Drivers reported the damage near junction 23 on the clockwise section of the motorway as they hit the jagged bump at speeds of up to 70 miles per hour.

The weekend's soaring temperatures, which reached more than 30 degrees, are being looked at as a possible cause.

The Highways Agency closed the clockwise carriageway at the scene between 5pm on Sunday and 5.30am this morning (Monday), while repairs were carried out.

A Highways Agency spokesman said: “It is still very early days and our investigators are looking at what caused this. Our priority was to get the road resurfaced so we could open it up again this morning.

“It is not something that happens very often. Generally when we have road surface problems it is due to a fuel spillage but this is a little more unexplained.

“We have completed the resurfacing to address the ridge in the road – two bits of tarmac had basically been pushed together and forced up.

“Heat is one of the things we’re looking into as a possible cause but it is not being addressed as the main factor at the moment.”

The damage occurred near to the Potters Bar junction of the M25