West African leaders have pledged $1 billion to combat the spiraling threat of Islamist militancy in the region, the head of the regional ECOWAS bloc said on Saturday.

Groups with links to al-Qaida and Islamic State have strengthened their foothold across the arid Sahel region this year, making large swaths of territory ungovernable and stoking local ethnic violence, especially in Mali and Burkina Faso.

The fifteen members of the West African bloc and the presidents of Mauritania and Chad had gathered for an extraordinary summit in Burkina Faso's capital, Ougadougou, to address the growing insecurity.