Muslim extremists have continued to destroy the heritage of the ancient Malian city of Timbuktu razing tombs and attacking the gate of a 600-year-old mosque, despite growing international outcry.

The International Criminal Court has described the destruction of the city's patrimony as a possible war crime, while UNESCO's committee on world heritage was holding a special session this week to address the pillaging of the site, one of the few cultural sites in sub-Saharan Africa that is listed by the agency.

The Islamic faction, known as Ansar Dine, or "Protectors of the Faith," seized control of Timbuktu last week after ousting the Tuareg rebel faction that had invaded northern Mali alongside Ansar Dine's soldiers three months ago.

Over the weekend, fighters screaming "Allah Akbar" descended on the cemeteries holding the remains of Timbuktu's Sufi saints, and systematically began destroying the six most famous tombs.

A spokesman for the faction said they do not recognise either the United Nations or the world court.

"The only tribunal we recognise is the divine court of Shariah," said Oumar Ould Hamaha.

"The destruction is a divine order," he said. "It's our Prophet who said that each time that someone builds something on top of a grave, it needs to be pulled back to the ground. We need to do this so that future generations don't get confused, and start venerating the saints as if they are God."

Among the tombs they destroyed is that of Sidi Mahmoudou, a saint who died in 955.

Shamil Jeppie, who heads the Tombouctou Manuscripts Project at the University of Cape Town in South Africa, said that the destruction analogous to the demolition of the Bamiyan Buddha in Afghanistan. The Wahabi interpretation of Islam that Ansar Dine - like the Taliban - espouses is a narrow version of the faith, and stands in contrast to what he says is the history of Islamic learning.

The UN cultural agency has called for an immediate halt to the destruction of the sacred tombs.

For years before the north of Mali became a base for an offshoot of al Qaida, Timbuktu was a must-see for backpackers and package tour groups. Much of the city thrived on tourism, from young men who memorised the history of the tombs and details of the ancient manuscripts to in order to act as tour guides to the numerous hotels, nearly all of which are now shuttered.

Hamaha said he did not care about the impact that their actions will have on tourism. "We are against tourism. They foster debauchery," he said.

Scholars held out hope that the Islamists would not also attack the city's 20,000-catalogued manuscripts, some dating as far back as the 12th century. Beyond the tombs, the manuscripts are considered to be the real treasure of the region and library owners have succeeded in spiriting some of the manuscripts out of the city, or else buried them in secure locations.