Ancient rocks at a protected site in Pembrokeshire are being moved, damaged or stolen by visitors, conservations have warned.
Pembrokeshire Coast National Park Authority has urged people not to disturb rocks at Foel Drygarn and Carn Meini in the Preseli Hills.
It is illegal to damage or take the rocks which are from the same site as those used in Stonehenge's inner ring.
The area is part of the Mynydd Preseli Site of Special Scientific Interest.
The national park authority said the hills were made up of prehistoric monuments in a landscape of natural cliffs and crags and people may be unaware of their protected status and significance.
Last month students from Pembrokeshire College's Army preparation training course helped repair one of the cairns at Foel Drygarn and record the damage of hammered and chipped stones at Carn Meini.
Community archaeologist Delun Gibby said: "The group began at Foel Drygarn by repairing holes in the cairn that had been created by walkers wanting shelter.
"This Bronze Age site is a scheduled ancient monument, so creating shelters is actually damaging the monument. We have now in-filled the holes to stop them getting deeper.
"At Carn Meini we found a number of stones that had been hammered and a stash of broken up bits of bluestone. It may well be that people have no idea that it's against the law to move or damage these stones."
Carn Meini's famous bluestone dolerite rocks were used to build the inner ring of Stonehenge and the debate about how they were transported - by man power or by glacier - continues.
Last year, experts and the park authority urged visitors to leave the landscape as they found it after pieces of bluestone were taken from Carn Meini.