"Unscrupulous" metal detectorists who hunt treasure under cover of darkness are damaging farmland and stealing Suffolk's heritage, a top rural police officer has warned.

The county is a particular target for illegal metal detecting, known as nighthawking, due to its rich Anglo-Saxon heritage and offenders often search online for potentially fruitful sites.

Sergeant Brian Calver, from Suffolk police's rural crime team, said the "vast majority" of detectorists are law-abiding and responsible, but those who do it illegally are "unscrupulous".

East Anglian Daily Times: Sargent Brian Calver is part of the wildlife department in the policeSargent Brian Calver is part of the wildlife department in the police (Image: Charlotte Bond)

"If you can imagine an area that's got history attached to it, an old Roman fort or an old Roman settlement, you've got all the archaeology left behind," he said.

"The people in the know who do this, they know these places, they can go online, there are forums and websites where they can look at these places and know exactly where to target.

"An awful lot of the landowners won't allow them to metal detect there because they don't want it on their land. Other people have got land with scheduled ancient monuments on it where they can't permit it. You need permission from the secretary of state to metal detect on land that's got a scheduled monument on it.

"The vast majority of detectorists are law-abiding people who belong to groups and clubs and they report all their findings and do the right thing.

"But the sort of people who are involved illegally are unscrupulous. When you look at their backgrounds, they've got some fairly nasty criminal history."

Sgt Calver said nighthawking is "under-reported" and stressed how it can lead to a loss of heritage in the county.

"People might say, 'Well, what's the problem with it, they are only finding a few bits and bobs?' but that could be something that is worth thousands, not to mention the loss of heritage that is gone forever and the damage caused," he said.

"That could be a vital bit of information that could really increase our knowledge of the history and heritage of the country.

"The bottom line is that it is theft. If they haven't got permission to be there, they are committing acts of theft. It is very under-reported, the vast majority of the public are unlikely to ever see it.

"We're trying to encourage the public to call 999 because it is a crime in progress because they could have something in their pocket worth thousands of pounds let alone the damage they are causing to the land. It probably goes on an awful lot more than we know about."

More information about rural crimes and advice on contacting police can be found here.