A man picks up an item belonging to a student at the site of a bomb blast in the university town of Zaria, Nigeria.

Abuja - Nigerian troops have arrested the suspected mastermind of bombings in the central cities of Jos and Zaria this week that killed at least 69 people, the defence ministry said on Thursday.

No one has taken responsibility for the attacks but they bore the hallmarks of Islamist sect Boko Haram, which has been waging a six-year insurgency in Africa's largest oil producer.

“The highly placed terrorist was arrested with two others who were in his company. One of them was however shot while trying to escape,” the defence ministry said.

The suspect was picked up at a checkpoint in the north-east city of Gombe, on the fringes of Boko Haram's north-east stronghold, it added.

Last week, more than 200 people died in a string of attacks in Africa's most populous nation, piling pressure on new President Muhammadu Buhari who is working with neighbouring states to quell the insurgency.

A joint operation by Nigeria and its neighbours has reduced attacks in recent months but bombings in the centre of the country suggests Boko Haram may be shifting its focus further south and west, towards the capital, Abuja.

Boko Haram has been trying to establish a state adhering to strict sharia law through an insurgency that began in 2009. It controlled an area larger than Belgium at the end of 2014.