French and Malian troops have entered the historic city of Timbuktu, after the Islamist rebels who controlled the city for ten months fled into the desert.

Before they left, the rebels set fire to an unknown number of ancient manuscripts dating back to the Middle Ages.

The rebels systematically destroyed cultural sites in Timbuktu, including the ancient tombs of Sufi saints, which they denounced as contrary to Islam, saying they encouraged Muslims to venerate saints instead of God.

The Islamists emptied the library's shelves and burned a pile of some of Timbuktu's 20,000 irreplaceable manuscripts in the days before they withdrew.

Some manuscripts had been removed from Timbuktu or hidden away for safekeeping from the Islamists.

Just over two weeks after the French began their military intervention in Mali, French and Malian forces arrived in Timbuktu overnight, a French military spokesman said.

French helicopters aided the ground forces who came from the south as French paratroopers landed north of the city, he said.

Several days before the ground assault, French military aircraft bombed rebel targets, including a house that used to belong to former Libyan leader Muammar Gaddafi, and was being used as the rebels' headquarters, Sky News reported.

The French have said Mali's military must now finish the job of securing Timbuktu.

The Malians have generally fared poorly in combat, often retreating in panic in the face of well-armed, battle-hardened Islamists.

Mali's Islamists still control the provincial capital of Kidal north of Timbuktu and are believed to have dug a network of tunnels, trenches and caves from which they can launch attacks.

French forces reached Timbuktu after a journey north through inhospitable desert conditions.

One of the French officers said the large military transport vehicles kept getting stuck in sand and mud, slowing the convoy's progress.

On their way to Timbuktu, the troops passed through the small town of Niafunke, where they were welcomed by cheering locals waving French flags.

The militants seized Timbuktu last April and began imposing a strict Islamic version of Shariah, or religious law, across northern Mali, carrying out amputations and public executions.

Timbuktu was for centuries a seat of Islamic learning and a major trading centre along the North African caravan routes that carried slaves, gold and salt.

The destruction of Timbuktu's manuscripts recalls tactics used by the Taliban in 2001 when they blew up a pair of giant Buddhas carved into a mountain in Afghanistan.