The National Trust is to carry out a drone survey of the fire-damaged Dunwich Heath amid fears that the inferno has exposed unexploded bombs from the Second World War.

The conservation charity is warning people to stay away from the “dangerous” area, with all public rights of access currently suspended.

More than 100 hectares of heathland habitat have been destroyed by fire at the Suffolk reserve since it took hold around two weeks ago, the National Trust said.

The fire service said on Monday that the fire has been stood down as a major incident but crews remain on scene damping down the affected area and monitoring for hotspots.

Matt Wilson, coast and countryside manager for the National Trust’s Suffolk and Essex Coast portfolio, said: “There’s no right for people to access this site at the moment because it’s dangerous.”

He said that during the Second World War, Dunwich Heath was used for training for Operation Kruschen, “which was looking at planning for the D-Day landings”.

“Across the landscape, features similar to German fortifications were set up and used to train Allied troops,” he said.

“During this fire event, at least two unexploded ordnance have been found and they’ve had to be remote detonated.”

He said that last week, the fire service called the bomb squad out to a phosphorus mortar just over the boundary into Minsmere, near to the reserve.

He said that the second unexploded ordnance that was discovered was a mortar fuse.

Mr Wilson said it is “likely there will be more” unexploded ordnance.

He said much of the site had been “covered by vegetation for decades”.

“Now there’s no vegetation barrier so theoretically people could, when they’re allowed access back in, walk across the landscape and come across something that has been buried since the 1940s,” he said.

“Out on site, our biggest priority is the unexploded ordnance surveys.

“We’re looking at doing low-level drone surveys looking for ferrous metals.”

He said that while tackling the fire, the fire service moved ground to create new fire breaks.

“We’ve got a lot of disturbed ground that wasn’t disturbed before… a huge amount of earth has been moved and there’s a really high risk that within that earth movement there could be unexploded ordnance,” said Mr Wilson.

The drone survey aims to establish safe routes on site before experts move onto soil testing.

“The most important thing for us now is to emphasise that the site is closed,” said Mr Wilson.

“It’s closed for really good reasons.

“I know there will be a fascination with disaster tourism and people wanting to come and see the damage for themselves, but the site is closed and it will remain closed until such time as we know that it’s safe to be able to come back in and we can’t put a timescale on that.”

He said that the fire service and police “have had to help people off site who have wandered in during an active fire event and got disorientated”.

“We’ve got a security team on at the moment to help us monitor,” he said.

“They’ve seen people running on the road and walkers and cyclists trying to get through.

“The mind boggles a little bit about why people think it would be appropriate to come.”

He said the site has yet to be handed back to the National Trust and described the fire damage as “extensive”.

“Almost everything has gone,” he said.

“What’s left is skeletons of gorse and trees that clearly have scorch damage in the distance.”

He said that with “hotter, drier summers, potentially we’re going to see this sort of incident here and elsewhere more often”.

He said there had been fire breaks but “this was such an unusual event and the severity of the fire, with the best will in the world anywhere in the country, wouldn’t have fire breaks that could cope with 40-metre flames and that radiated heat that’s making trees spontaneously combust”.

He said that once assessments have been completed, which are expected to take months, experts would consider how they may be able to make the habitat wetter by adding different features.