MALI (AFP) — Muslim jihadists occupying northern Mali said they had cut off the hand of a thief in accordance with strict Islamic law which they have imposed on the population.

The first reported amputation since the extremists seized the north of the country four months ago came as diplomats warned of a ticking time-bomb which could put the world at risk if the region becomes a safe haven for terrorists.

As west African mediators attempt to engage in talks with the Islamist groups and the option of military intervention lies untried, the extremists carried out a further grisly religious punishment.

They have already stoned an unwed couple to death and beaten other people.

"Yes, I confirm it. We applied sharia in Ansongo yesterday. The hand of a thief was cut off. Sharia demands it," a leader of the Movement for Oneness and Jihad in West Africa (MUJAO), Mohamed Ould Abdine, told (AFP).

A local government official in the town south of Gao, one of the chief centres of the vast desert region in northern Mali, said he witnessed the public amputation.

"I am in Gao now, but yesterday I was in Ansongo. There was a lot of blood when the hand was cut. It was the hand of a thief who stole a motorbike," he told AFP.

Abdine said the sentence was "the law of God".

On Sunday scores of protesters swarmed the main square in Gao to prevent Islamists from cutting off the hand of a another thief, but Abdine said the sentence had only been put off.

"We will do the same thing in Gao soon. Last time we postponed because of the intervention of important people and not the population. The population can't do anything," he said.

In the small town of Aguelhok, another armed Islamist group, Ansar Dine (Defenders of Faith), publicly stoned an unmarried couple to death in late July. They have forced women to cover up and whipped smokers and drinkers.

In the ancient city of Timbuktu, Ansar Dine have destroyed World Heritage shrines dating back to the 15th century, denouncing them as idolatrous.

The Islamist groups, which security experts say are acting under the aegis of Al-Qaeda in the Islamic Maghreb (AQIM), seized key northern cities in the chaos following a coup d'etat in Bamako on March 22.