MILLIONS of pounds may be needed to save one of Hampshire's best known landmarks from erosion, the Daily Echo can reveal.
Hurst Castle was built in the 16th century to counter the threat of a French attack and also helped combat the Nazis during the Second World War.
But the 470-year-old structure, near Keyhaven, is facing a new danger.
Huge waves are damaging part of the castle following a sudden shift in the pattern of coastal erosion, sparking fears that public access could be restricted unless urgent action is taken.
Emergency talks have taken place involving representatives from New Forest District Council and English Nature, which owns the fort.
David Jupp, chairman of Friends of Hurst Castle, said millions of pounds could be needed to be spent on protecting the structure.
“The pattern of coastal erosion has changed dramatically in the past six months,” he said. “Shingle separating the waves from the castle is being eroded away, threatening part of the ancient monument. Some of the stone cladding has fallen away and part of the foundations has been exposed.
“It’s very difficult to judge what will happen next but we could lose portions of the southern wall if nothing is done. That would call into question the safety of the structure and public access might be denied.”
Built in 1544, the castle occupies an exposed position at the end of Hurst Spit.
In the 1990s more than 600,000 tonnes of gravel were brought in to strengthen the Spit as part of a £5m sea defence scheme. The project was deemed so successful that plans to top-up the shingle after ten years were deferred.
Mr Jupp said huge lumps of granite now needed to be placed in front of the castle to break up the wave action.
An English Heritage spokesman said: “Coastal protection works were undertaken around 20 years ago and these had |been effective until relatively recently.
“However, this winter has seen an area of erosion develop along the east wing, where the level of shingle along the beach has dropped in some areas.
“This has resulted in part of the concrete foundations being exposed to high tides.”