The Islamic State (IS) group has confirmed for the first time that it is engaged in heavy fighting with al-Qaeda linked militants in Mali and Burkina Faso.

In its online publication, al-Naba, it described members of al-Qaeda's Sahel affiliate as apostates and wild dogs.

IS said it had targeted its rivals with a suicide bombing and other attacks.

It was reported earlier that al-Qaeda militants had rejected an IS offer of a ceasefire in exchange for the release of IS prisoners and the payment of blood money for the deaths of IS militants.

Islamist attacks have intensified in the Sahel in recent months.