Isis leader calls on Muslims to 'build Islamic state'

The leader of jihadist militant group Isis has called on Muslims to travel to Iraq and Syria to help build an Islamic state, in an audio message.

Abu Bakr al-Baghdadi called on Muslims to immigrate to the "Islamic State", saying it was a duty.

Isis says it is forming an Islamic state, or caliphate, on the territories it controls in Iraq and Syria.

Jeremy Bowen reports from Baghdad.