Vandals hit Bronze Age Maen Llia standing stone
Vandals who daubed a Bronze Age stone in the Brecon Beacons National Park with a smiley face have been criticised.
The 3.7m (12ft) Maen Llia standing stone is recognised as a site of national archaeological importance.
It is likely that the stone was erected in the Late Neolithic or Early Bronze Age between 2500 and 1800BC.
The graffiti is being removed from the stone which is situated between Heol Senni and Ystradfellte.
Removal will be carried out between the national park authority, landowners and the Welsh government's historic environment service Cadw.
Natalie Ward, heritage officer for Brecon Beacons National Park Authority, said: "The heritage of the national park is the legacy left to us by our ancestors and it contains a wealth of information about past peoples and their lives.
"The person who did this may well think it was harmless fun but archaeological sites like Maen Llia are fragile and causing damage to a scheduled ancient monument is a criminal offence.
"Criminal acts like this can cause irreversible damage."
Causing damage to a scheduled ancient monument is a criminal offence, and the graffiti at Maen Llia has been reported to Dyfed-Powys Police.