Police in the Western Isles are carrying out inquiries into a reported unauthorised excavation of an Iron Age galleried dun.
Dun Torcuill sits on an uninhabited island on a loch on North Uist and is considered to the finest and best preserved example of its type across both Uists and Benbecula.
As a scheduled monument, Dun Torcuill is legally protected and recognised as being of national importance. Officers are liaising with Historic Environment Scotland to establish the full circumstances.
The damage was reported to police on Tuesday, 22 October and comprises the clearance of tumbled stone from the site.
Sergeant Gavin McDevitt of Lochmaddy Police Station said: "Damaging or removing any part of a scheduled monument is a criminal offence. In this instance, there is the potential for destabilisation of the monument, and/or the loss of archaeological deposits previously protected by the tumbled stone.
"It is an offence under the Ancient Monuments and Archaeological Areas Act 1979 to undertake works without Scheduled Monument Consent. The penalties for offences under the Act are considerably higher than those for damage to property or vandalism offences, with fines ranging up to £50,000 or prison sentences of up to two years.
"Police Scotland and HES are working closely to investigate this report and we are particularly keen to hear from anyone who has visited the monument within the last six months.
"If anyone has any information that could help, please call 101 and quote the Police Scotland reference number 1652 of 22 October."