Gunmen believed to be Boko Haram insurgents have killed at least 15 people in north-eastern Nigeria in the course of the country’s presidential and National Assembly elections holding since morning.

A Reuters report quoted the police as confirming that Boko Haram insurgents launched several attacks on voters in the North-East, killing three voters in Yobe State and three more in Gombe State.

The report quoted a spokesman for the opposition All Progressives Congress (APC) as saying that at least eight people were also killed by unidentified gunmen.

Boko Haram leader Abubakar Shekau has threatened to kill Nigerians who go to vote. A string of victories against the militants by Nigeria and neighbours Chad, Cameroon and Niger has reclaimed much of the territory the Islamists controlled earlier this year, but they retain the ability to mount deadly attacks on civilians.

“Separately, gunmen shot dead a soldier in an ambush in the southern oil hub of Port Harcourt, a hotbed of Jonathan support but a city with a long history of political thuggery,” Reuters said.

•Photo shows Boko Haram leader Shekau.