Police officers have been drafted in to patrol Hadrian’s Wall to stop it from being damaged by rogue metal detectorists.

The treasure hunters – known as “nighthawks” – have been stealing ancient artefacts from sections of the 1,900-year-old UNESCO World Heritage Site.

The 73-mile-long wall is the largest Roman archaeological feature in the world and was built under the orders of Emperor Hadrian in AD122.

Historic England said there has been a surge in “nighthawks” searching illegally for Roman loot under the cover of darkness.

In recent years, there have been several reports of targeted illegal metal detecting along the wall, with Corbridge the worst-hit area.

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The Roman fort and town is protected as a scheduled monument where using a metal detector without proper authorisation is a criminal offence.

Northumbria Police has teamed up with Historic England to put up warning signs at Corbridge in a bid to tackle unlawful metal detecting.

Mike Collins, Historic England’s inspector of ancient monuments for Hadrian’s Wall, said vandals were robbing the public of knowledge that could be gleaned from the ancient artefacts.

He said: “Most people who go metal detecting comply with the law and the codes of practice for responsible metal detecting, but there’s a small but significant element – known as ‘nighthawks’ – who are damaging and stealing parts of this internationally important historical site.

“Essentially, they are robbing us all of parts of our national heritage as the artefacts they take or destroy could have added to our knowledge of Roman Britain.

“Illegal metal detecting at Hadrian’s Wall is particularly a problem at this time of year as adjacent farmland is being cropped and ploughed, making it easier for criminals to access and steal historic artefacts.”

Historic England said there had been a spate of nighthawking incidents at other sections of the wall and that it was working with police to identify the offenders.

PC Lee Davison said: “We work very closely with Historic England and we are proud of the heritage sites we have here in the Northumbria force area.

Police are to patrol Hadrian's Wall to protect it from being damaged by rogue "nighthawk" metal detectorists. (SWNS)

“Protecting those historic sites is very much a partnership effort and it saddens us that they can often attract criminal activity.

“It may be the case that many people aren’t even aware they are committing a criminal offence but we hope we can work closely with Historic England to educate the public.

“We will be conducting patrols to deter criminal behaviour and if we identify anyone who has been stealing historic artefacts then they will be arrested.”

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Hadrian’s Wall was a defensive fortification in the Roman province of Britannia.

The original construction of Hadrian’s Wall began in AD122 and the 73-mile barrier, which runs from the banks of the River Tyne to the Solway Firth, took just six years to complete.

The wall, which was designed by Emperor Hadrian, marked the northern limit of the Roman Empire.