Thousands of drivers could have speeding fines cancelled after a fault saw some cameras falsely triggered on English motorways and A roads.

And tens of thousands of drivers will have speed awareness courses cancelled as the government orders National Highways to look back at six years of speed camera data.

National Highways said it had found 2,650 wrongful speed camera activations since 2021 due to a delay between cameras and variable speed signs.

Not all camera activations are enforced, so not all of the wrongful activations will have resulted in fines.

Affected drivers will be contacted by police and be reimbursed for any fines while points will be removed from their licences where needed.

More than 36,000 drivers have been told by police their speed awareness courses are being cancelled as a precaution while the speed camera issue is investigated.

Police forces are also thought to be discontinuing thousands of other prosecutions, regardless of whether they were affected by the issue.

Transport minister Simon Lightwood said the government will compensate any affected drivers, refunding speeding fines and rescinding points from licences.

“Steps will be taken to remedy any incorrect prosecutions,” he said in a written statement to parliament.

National Highways apologised for the error.

“Safety is our number one priority,” said chief executive Nick Harris.

“All drivers should continue observing the posted speed limits as normal. Anyone who has been impacted will be contacted by the relevant police force.”

The agency said a temporary fix had been rolled out, providing an extra layer of data from the cameras to police forces so they can filter out any faulty captures.

But the agency gave no clear timeline as to when a permanent fix would be in place.

National Highways, which runs England’s motorways, blamed an “anomaly” in how variable speed cameras were interacting with signs on some A roads and motorways.

It meant a delay of around 10 seconds between cameras and relevant variable speed signs, meaning some drivers were incorrectly identified as speeding after the limit had changed.

So on a road where the speed limit increases, a driver may see a sign saying 60mph, but the camera recording it may still be working on the basis of a previous 40mph speed limit.

National Highways said the 2,650 incidents since 2021 represent fewer than two each day, compared with more than six million activations of speed cameras on the affected roads over the same period.

It said the anomaly has impacted 10% of England’s motorways and major A roads.

The fault affects 154 cameras out of a total of 400 across the entire motorway network – all of the variable speed cameras on smart motorways, and a section of the A14 between Huntingdon and Cambridge plus the A1 approach junction to the A14.

Andy Walpole, 55, from Swindon was one of those who was incorrectly landed with a ticket for speeding on the M25 between junction 9 and Cobham services.

“I was adamant I wasn’t speeding. I drive for a living, so I adhere to the variable speed limits within a mile an hour, so I knew I wasn’t,” he told the BBC.

He opted to pay for a speed awareness course rather than challenge the penalty, because he felt it was difficult to mount a successful appeal.

Though he was refunded the cost of the course, he says: “How can we have trust and faith in the system now?”

He also wonders how many people who chose to take points on their licence would have ended up with higher insurance premiums as a result of an unsafe conviction.

“What if you took your car insurance out the day after you’d taken the points? You declared those points on your insurance — where do you stand then?”

National Highways is working with police to check activations and promised nobody would now be wrongly prosecuted.

Meanwhile, police forces have stopped issuing fines from variable cameras until they have confidence in their accuracy.

National Highways said it will increase the use of traffic patrol officers to enforce speed limits in the meantime.

Lightwood warned drivers that “if you break the law, you can expect to be punished”.

A Department for Transport spokesperson said: “We apologise to anyone who has been affected. Safety was never compromised, and we are working with policing to ensure nobody is incorrectly prosecuted in future.

“Enforcement is still in place, and the public can remain confident that only motorists who break the rules will be penalised.”