Motorists face an indefinite 50mph speed limit on a key stretch of motorway as the government continues to prepare for Brexit.

Highways chiefs have revealed overnight closures on the M20 will come into force from Saturday as work to install a contraflow system is carried out.

The system is part of the government's Operation Brock plan, a modification of Operation Stack where lorries will park on the M20 coastbound while traffic passes in both directions on the London-bound carriageway.

It means an eight-mile stretch of the M20 between Ashford and Maidstone heading towards London will be closed to traffic overnight from this weekend.

During the day, a 50mph speed limit will be put in place from junction 9 to 8, with the Department for Transport giving no indication of when the restrictions will come to an end.

The scheme is a key part of a series of contingency plans that form Operation Brock.

It will be triggered if there is disruption and delays at the channel ports or at Eurotunnel, leaving lorries unable to cross the English Channel and causing huge backlogs.

In the event of a no-deal Brexit, problems are likely given the amount of time it will take to carry out customs checks on freight traffic.

It is not clear exactly how many night closures are planned or the times it will close and reopen.

A Department for Transport spokesperson said: “We are working hard to deliver a deal with the EU.

"However, as a sensible government we continue to make plans for all eventualities, and will ensure Operation Brock is fully functional if needed.

“This work is essential to keeping Kent traffic on the move during cross-Channel disruption, enabling people to get to work or school and businesses to reach customers.”

Highways England will start the work on Saturday February 9. Overnight closures will be in place to ensure disruption to motorists is kept to a minimum.

A 50mph speed limit will be implemented for driver safety when the motorway reopens.

Ashford MP Damian Green said this will come into force from Tuesday, February 12.

During the overnight closures a clearly signed diversion will be in place via the A20.

A Freedom of Information request by KentOnline last year revealed that it could take up to 14 days to install the barrier.

The DfT says if drivers need to travel while work is taking place, they should plan ahead and allow more time for their journeys.

KentOnline has asked for details on the times the motorway will be closed and whether there will be other overnight closures.