An historical landmark in the Broads has been irreparably damaged by vandals.

St Benet's Abbey, a medieval monastery established in the 9th century, was defaced with carvings etched into the gatehouse's historic limestone.

The damage comes as Norfolk Archaeological Trust (NAT) has said there has been an increase of heritage crimes at Norfolk's historical sites in the past 12 months.

Natalie Butler, director of NAT said: "Its just devastating to see the damage done to this historic building.

"While the gatehouse has a collection of old carvings from over the years, a lot of new marks have been made last month.

"It seems it was likely done by one group who visited the gatehouse and decided to scrape their names into the limestone, which cannot be removed without further damaging the historic fabric of the building."

Norfolk Police have said they are continuing to investigate the crime, which is believed to have happened between 1am on September 21 and 11pm on October 8.

On Thursday, anti-vaccine graffiti was also found at the Caistor Roman Town near Norwich.

This graffiti was removed but it shows the extent of the problems faced at heritage sites in the county.

The Historical Monuments and Archaeological Objects Order (1995) aims to afford protection to heritage sites from but it seems not everyone is aware of these laws.

A spokesperson for Norfolk Police said: "“We are aware of heritage crimes taking place in Norfolk and always endeavour to investigate as we would any other crime and encourage people to report them to us.

"The nature of many of these places of interest means they can be quite rural and isolated and the crimes are often not spotted when they happen but witnesses and information can be crucial.

"This can include areas not necessarily overlooked by other properties or CCTV which can limit our forensic opportunities."

Ms Butler added: "Crimes like these has a devastating impact on historic sites.

"It's been a horrendous problem this year costing lots of time and money. with the number of reports are well into double figures.

"At the beginning of the year we even had a donation pot and contents stolen. As well as graffitiing, we have also seen people using metal-detectors at heritage sites, which is also illegal.

"People need to understand that these places are really special and part of our history. We all need to look after them so they are there for future generations.

"If you see someone damaging heritage sites or metal detecting, call the police."

Anyone with information concerning St Benet's Abbey can contact PC Darby at Norfolk Constabulary on 101 quoting crime reference 36/82054/21.