Al-Qaeda chief Ayman al-Zawahiri has pledged allegiance to the new head of the Taliban.

The announcement came in an audio message, which could not be immediately verified but bore all the signs of an Al Qaeda video.

The pledge to Mullah Mohammad Akhtar Mansour is expected to boost his accession to the head of the extremist group following the death of Taliban founder Mullah Mohammad Omar.

Some senior members of the group have questioned his appointment, creating potential divisions.

Offering allegiance to the Taliban also sends a message to the self-proclaimed Islamic State, which is challenging Al-Qaeda for leadership of the global jihadist movement.