Residents of Timbuktu in the west African country of Mali say Islamists have destroyed the 15th century shrine of a famous Muslim saint.
They say the mausoleum of Sidi Mahmoud is ruined and that other shrines are being attacked.
The BBC reports fighters from the Ansar Dine group began attacking the shrines on Saturday morning, using shovels and pickaxes.
Islamists regard the shrines as idolatrous.
UNESCO has described the destruction as tragic.
The shrine of Sidi Mahmoud was one of 16 in the city. It was previously attacked in April and set on fire by armed men from Ansar Dine.
Timbuktu, an ancient trading city on the edge of the Sahara Desert, is known for its distinctive architectural structures, constructed mainly from mud and wood. It was a centre of Islamic learning from the 13th to the 17th Centuries.
In addition to the shrines, Timbuktu is home to some 700,000 ancient manuscripts held in about 60 private libraries.
Ansar Dine said no site would be safe in Timbuktu.