The National Monuments Service has confirmed that it is investigating a report of serious damage to a 3,000-year-old hillfort near Cavan town.
It said it received a report of the damage on 15 May and the monument has since been inspected.
The vitrified hillfort is a listed monument on private land located at Shantemon, outside of the town and is understood to be the only confirmed example of its type in the country.
The National Monuments Service said the inspection report is now being examined and it could not comment any further.
Vitrified forts are stone enclosures where the walls have been subjected to intense heat, which fused the rock to give them a glass-like feature.