Unknown attackers kidnapped three Europeans and killed a fourth in the historic northern Mali town of Timbuktu on Friday, a Malian government source said.

The source, who declined to be identified, said the person killed was German and had tried to resist the attackers. The nationality of the others was not immediately known.

The attack came a day after two French nationals were kidnapped from their hotel in the same region, where local agents for al Qaeda in the Islamic Maghreb operate.

The French nationals were kidnapped in the town of Hombori, close to the border with Burkina Faso.

The increased risk of kidnappings, either by Islamists or by local gunmen cooperating with them, has made large tracts of Mauritania, Mali and Niger no-go areas for Westerners.

Timbuktu, founded a thousand years ago and famous as a major trading centre for gold and salt, was one of the centres of a local tourist sector that has now all but ground to a halt.

Western nations led by France and the United States are trying to improve regional cooperation but efforts have been undermined by a lack of resources, regional rivalries and a degree of local complicity.

(Reporting by Tiemoko Diallo; Writing by Mark John; Editing by Jon Hemming)