PARIS — A vast new sanctuary is emerging for al-Qaeda’s African followers in the desert wastelands of northern Mali, where Tuareg secessionists, allied with extremist Muslim guerrillas, have shaken off government rule and declared an independent Islamist state.

The haven taking shape in West Africa — more than 250,000 square miles, including the legendary city of Timbuktu — risks turning into an outland much like the remote areas of Afghanistan, Pakistan, Somalia and Yemen where terrorists linked to al-Qaeda seek safety from U.S. and other efforts to hunt them down, according to European diplomats, academic experts and reports from the region.