Timbuktu, Mali - Islamist militants in Mali have attacked one of the most famous mosques in the historic city of Timbuktu, residents say.
Armed men broke down the door of the 15th-Century Sidi Yahia mosque, a resident told the BBC.
The Ansar Dine group, which is said to have links to al-Qaeda, seized control of the city earlier this year.
It has already destroyed several of the city's shrines, saying they contravene its strict interpretation of Islam.
Ansar Dine spokesman Sanda Ould Bamana told the BBC that his movement had now completed nearly 90% of its objective to destroy all mausoleums that are not in line with Islamic law.
He said Sharia did not allow the building of tombs taller than 15cm (6 inches).
The new chief prosecutor of the International Criminal Court, Fatou Bensouda, on Sunday condemned the destruction as a "war crime", reports the AFP news agency.
The UN cultural agency Unesco and Mali's government have called on Ansar Dine to halt its campaign.
Unesco has also expressed concern that valuable artefacts and manuscripts may be smuggled out of the region and has urged neighbouring countries to prevent this.
The 55-nation Organisation of the Islamic Conference said in a statement that the sites Ansar Dine had attacked were "part of the rich Islamic heritage of Mali and should not be allowed to be destroyed and put in harm's way by bigoted extremist elements".
The site of Sidi Yahia is one of the three great mosques of Timbuktu.
The door which has been smashed had been left sealed as it led to the sacred tomb of saints.
Some witnesses started crying when they saw the damage, AFP says.
Some local people believe that opening the door will herald misfortune.
Timbuktu owes its international fame to its role as a centre of Islamic learning, based in its three large mosques, in the 15th and 16th Centuries.
Timbuktu is also known as "City of 333 saints", which originate in the Sufi tradition of Islam.
Ansar Dine's Salafist beliefs condemn the veneration of saints.
The group seized control of Timbuktu in April, after a coup left Mali's army in disarray.
Initially, it was working with secular ethnic Tuareg rebels demanding independence for northern Mali's desert territories but the groups have recently clashed and Islamist forces are in control of northern Mali's three main centres - Timbuktu, Gao and Kidal.