By seizing hundreds of hostages at a gas plant in the Algerian desert, al Qaeda-linked militants angry at French intervention in Mali sent a clear message: they could strike anywhere in the Sahara.

Many experts now believe the sight of a former colonial power leading unprepared West African armies into war against Islamists in Mali could spark similar attacks across a swathe of smaller, more vulnerable nations to the south.

Islamist fighters who escape the French onslaught are likely to scatter, with some remaining in Mali to fight a guerilla-style war while others trickle across its porous borders into countries where pockets of radicalism already exist.