A donkey strapped with explosives was used to ambush the convoy of the governor of Nigeria’s north-eastern Borno state.
Governor Babagana Zulum was returning to the state capital, Maiduguri, from Baga town when they were ambushed.
Sunday’s attack came two days after he had survived another attack while travelling to an area near Lake Chad.
Death toll from the incident rose to 33.
Among them were 24 police officers and soldiers and four civilians.
Islamic State West Africa Province (Iswap) militants, who were behind the attack, split from Boko Haram, an Islamist group that launched its insurgency in north-eastern Nigeria a decade ago.
The group’s campaign of violence has spread to neighbouring countries, killing more than 30,000 people and forcing two million from their homes, according to the UN.
