Drivers are being warned to ignore satnavs and follow official diversion routes ahead of an “unprecedented” closure of the M25 this weekend.

National Highways issued the alert as it prepares to close a five-mile stretch of the motorway in Surrey from 9pm on Friday until 6am on Monday.

The Government-owned company estimates that drivers who follow signs for diversion routes on A-roads will have an hour added to their usual journey times between junctions 10 and 11, which will be shut in both directions.

It is concerned that some may try to find alternative routes via minor roads.

Worcester News:

National Highways project lead Jonathan Wade said how well the area copes with the M25 closure will partly depend on whether drivers stick to official diversions.

He told the PA news agency: “How many people are going to take the initiative and try and use satnavs?

“There’s probably a greater risk of congestion by people just doing their own thing and thinking they can perhaps beat the signs and find a shorter or quicker route.

“That will cause further congestion on some of the key junctions so please avoid doing that if at all possible.”

National Highways senior project manager Daniel Kittredge said: “If people move away from diversion routes that we prescribe, it creates additional issues in different parts of the road network.

“The majority of the time that will be local roads, so that really impacts residents in those particular areas.

“That’s why we’re trying to encourage people to not follow the satnav.

“Stick on the prescribed diversion route. It’s going to be more suitable for your journey.”

National Highways said the action is necessary to enable a bridge to be demolished and a new gantry to be installed.

The organisation believes only one hour will be added to journeys as a result of the closure.

The M25 normally carries between 4,000 and 6,000 vehicles in each direction per hour from 10am until 9pm at weekends between junctions 9 and 11.

Four more daytime closures of the motorway will take place up to September.

The project, due to be completed in summer 2025, will increase the number of lanes and make it easier to enter and exit the M25 at junction 10, which is one of the UK’s busiest and most dangerous motorway junctions.