A Kent MP is demanding an explanation from highways chiefs over a report suggesting contingency plans for Operation Stack may not be ready in time for Brexit.

The National Audit Office published a report last week that raised concerns time was running out to test and implement what has been dubbed “Operation Brock” along a stretch of the M20.

The scheme involves a contra-flow on the motorway designed to keep traffic moving in both directions.

Faversham and Mid Kent MP Helen Whately said she was “very worried” by the report.

“It’s completely unacceptable for Kent’s roads to be brought to a standstill, so I was very worried to read this report. Operation Brock must be ready for Brexit day, so that traffic can continue to flow, people can still get to work, children can get to school and businesses can still function – even if there is disruption at the border. Given that Kent is the gateway to Europe, this should be a national priority for the Government.”

As recently as last week, Highways England had assured her that the scheme was on track.

“Every time I’ve met Highways England, including just last week, they’ve reassured me that the temporary solution will be ready by next year. But this report suggests they are already behind schedule and there’s no room for further delay.”

“I’m writing to the chief executive of Highways England asking for a detailed explanation of how they will make sure our roads are ready for the day we leave the EU.”

Auditors warned “considerable work needs to be done” on the £20m plan designed to keep traffic moving after Britain leaves the EU.

A Government spokesperson said: “The NAO concludes that the Department is making a determined effort to ensure the UK transport system is fully prepared for EU Exit and acknowledges that the Department has already achieved a great deal.”