An unmarked HGV is being used to spot drivers using mobile phones, not wearing seatbelts, speeding and ignoring signs.

Police have been patrolling dual carriageways, including a 10-mile stretch of the A1 through Rutland, with PC Kieran Dempsey at the wheel accompanied by a 'spotter' officer equipped with digital cameras in the passenger seat.

The HGV is followed at a distance by up to four additional police vehicles.

The height of the HGV allows the spotter to see into other vehicles, while it can be driven at up to 80mph.

If a driver is caught committing an offence, other vehicles in the team are alerted by radio, catch up with the offender vehicle and wait until a suitable place can be found – usually a junction or layby – where the offender can be pulled over and questioned.

Minutes after setting off on Thursday, June 20, an offender was filmed using his mobile phone while driving at 60mph.

When pulled over, he argued at first that he was 'just vaping', but when confronted with video footage, which appeared to show him texting, he accepted his guilt, apologised and was given a ticket.

A man in a maroon Volvo was stopped next, who told officers he had heard the police HGV would be out and about. It didn't apparently make any difference – he was using his mobile phone on his lap to find an address, and was also given a ticket.

Sgt Stuart Parker, driving one of the unmarked vehicles, said: "The driver thought there was something suspicious when we pulled alongside him, but he was collecting his son from university and needed the location from his phone.

"He did apologise and asked if he could be 'let off' but that is not an option. We take motoring offences very seriously indeed. It only takes a second of lack of concentration to cause an accident and possibly a tragedy."

A man in a white van, filmed using his phone for several minutes, failed to notice the HGV that had pulled alongside him, or the officer in the passenger seat filming him.

He didn't even notice the marked police car when it pulled alongside.

He too claimed at first that he was 'only vaping' and had 'only glanced at his phone to see a message', but the video footage told a different story.

PC Dempsey said: "It never fails to shock me the risks that people will take when driving. They often see using a mobile phone while driving as a 'soft crime', and we hear them say when they are pulled over 'why aren't we out catching some 'real' criminals?'

"But moving vehicle crimes are very serious and we treat them as such. At these speeds one mistake can prove fatal, not only to the driver, but to other innocent road users."

He added that Operation Tramline, the name given to the use of the HGV and accompanying officers, is a message to drive safely and use the road system safely, of risk being caught.

The HGV is one of three available to police forces, funded by National Highways. More than 35,000 offences have been recorded by officers using the HGVs.

It is illegal to use a handheld mobile phone or similar device when driving, stopped at traffic lights or queuing in traffic. The minimum fine is £200 and six penalty points.

If taken to court, the maximum fine is £1,000 for motorcyclists, car and van drivers, or £2,500 for those behind the wheel of a lorry or bus.