Islamist fighters with ties to al-Qaeda have destroyed tombs classified as a UNESCO World Heritage site in Mali's historic city of Timbuktu, a resident and UN officials said Saturday.

Irina Bokova, who heads the UN Educational, Scientific and Cultural Organization, cited in a statement Saturday reports the centuries-old Muslim mausoleums of Sidi Mahmoud, Sidi, Moctar and Alpha Moya have been destroyed.

Resident Ali Yattara said Saturday that the Islamists began attacking the saints' tombs with shovels. He says they said they were responding to UNESCO's request on Thursday that the sites be put on the organization's "in danger" list.

Yattara said locals planned to fight back.

"The youth of Timbuktu is preparing to retaliate against the desecration of the graves of our saint," he said Saturday.

"Against the Islamists' weapons, we will fight with sticks and stones."

He said the Islamists don't approve of residents' high regard for the saints' tombs.

France condemns 'deliberate destruction'

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

Bokova called on "all parties engaged in the conflict to stop these terrible and irreversible acts."

On Thursday, UNESCO's World Heritage Committee, meeting in St. Petersburg, Russia, placed the mausoleums of Muslim saints on its list of sites in danger at the request of Mali's government.

France also condemned the "deliberate destruction."

Timbuktu was a centre of Islamic learning as far back as the 12th century.

Islamist fighters from the Ansar Dine group have declared that they now control the northern half of Mali after driving out an ethnic Tuareg separatist group. The rebel groups took advantage of a power vacuum created by a March coup in the capital to seize ground in the north.

The Islamists' growing reach is more worrying news for the landlocked West African nation of 15.4 million, which was plunged into chaos after the coup.