The Islamic State West Africa Province group and its rival Boko Haram have intensified their assaults on military bases in recent weeks, notably in Borno state -- the epicentre of an insurgency dating back to 2009.

According to an AFP tally, at least 10 military bases in the northeast have been attacked by jihadists in the last two months. At least 100 people, including civilians, were killed in a wave of attacks in April.

"Actions have been taken to ensure that we address the series of attacks that is ongoing," General Christopher Musa told troops in Borno's capital Maiduguri, promising that new materiel was being "brought into the theatre".

Musa added that conflict in the wider Sahel, including in Mali, Chad and Niger, "has put a lot of pressure on Nigeria and that's why you see recent attacks have occurred".

"Whatever is going on is just for a short while," he said.

Musa also suggested "physically fencing our borders, saying "there are countries that have fenced over a 1,500 kilometre (930 mile) stretch" -- roughly the length of the Nigeria-Niger frontier.

- Intelligence report warns of 'mutinies' -

While violence has fallen from its peak in 2014-2015, the governor of Borno recently warned that the military was losing ground to jihadists, and the spate of attacks this spring has put the conflict in the spotlight.

More than 40,000 people have been killed and two million displaced in northeast Nigeria since 2009, according to the United Nations.

The Multinational Joint Task Force, a coalition created by Nigeria, Niger, Cameroon, Benin and Chad to fight the cross-border armed groups, has been hampered recently by the withdrawal of Niger and threats by Chad to do the same.

According to a recent Nigerian intelligence report seen by AFP, however, some of the struggles have internal roots.

Late payment of salaries "has been a recurring problem", particularly in the northeast, it said.

The report further warned of "frustration and demotivation among security personnel, which could potentially lead to mutinies or unrest, if not urgently addressed".