Muslim hardliners known as Salafists have been blamed for destroying ancient stone carvings in Morocco's High Atlas mountains.
The rock engravings date back more than 8,000 years and include an image of the Sun depicted as a pagan god.
"They were destroyed several days ago," said Aboubakr Anghir of the Amazigh League for Human Rights.
"One of the carvings, called 'The plaque of the Sun', predates the arrival of the Phoenicians in Morocco."
The artwork was reportedly located in a well-known archaeological site in the Toubkal National Park, to the south of the city of Marrakesh.
The remote area is largely populated by Amazigh people, non-Arab tribes who are indigenous to North Africa.
"The information we have received from Amazigh activists in the area suggests Salafists were behind the act," said Ahmed Assid, a member of the Royal Institute for Amazigh Culture.
"This act follows a noticeable rise in Salafist activities in predominantly-Amazigh regions of Morocco to enforce a puritanical interpretation of Islam.
"Their view is that aspects of Amazigh culture, including pre-Islamic heritage, still present today defeat the purpose of the Islamic conquests."
Meryem Demnati, of the Amazigh Freedoms and Rights Watchdog, also confirmed the destruction of the carvings, known as petroglyphs, and said residents in the area blamed Salafists.
The ultra-conservative interpretation of Sunni Islam, which strictly prohibits idolatry, has been gaining power in North Africa - benefiting from wider freedoms since the pro-democracy uprisings in the Arab world last year.
The alleged destruction of the carvings in Morocco follow an arson attack by Salafists on one of Tunisia's main Sufi mausoleums on Monday.
The Saida Manoubia shrine in the west of the capital Tunis was burned down overnight.
Islamist fighters in Mali used pick-axes and shovels to damage the shrines of Muslim saints in the city of Timbuktu in June last year.