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

According to an AFP tally, at least 10 bases have been attacked in two months. At least 100 people, including civilians, were killed in attacks in April.

"Actions have been taken to ensure that we address the series of attacks," chief of defence staff General Christopher Musa told troops in Borno's capital Maiduguri, promising new material was being drafted in.

Musa said conflict in the Sahel states including 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 suggested fencing Nigeria's borders, saying "there are countries that have fenced over a 1,500 kilometre (930 mile) stretch" -- roughly the length of the Nigeria-Niger frontier.

While violence has fallen from its 2014-2015 peak, the governor of Borno recently warned that the military was losing ground to jihadists, and the latest attacks have put the conflict back 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.

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

According to a recent Nigerian intelligence report seen by AFP, there are also internal problems.

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

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

President Bola Tinubu this week called for the creation of a "forest guards" unit "to flush out terrorists and criminal gangs".

Nigeria's vast, often inaccessible forests have become havens for jihadist and armed criminal groups.

While the Nigerian army often works with local self-defence groups, questions remain over how the proposed forest guard be financed, work with existing security forces and even how long it would take to set up.