Nigeria's President Muhammadu Buhari has blamed some of the violence in the country on "disgruntled politicians".

He made the comments at Army Day celebrations in Borno State, according to a tweet from his personal assistant.

Nigeria's security forces are facing challenges on several fronts.

It continues to fight the insurgency from Islamist militants Boko Haram in the north-east of the country.

And in recent months, an age-old conflict in the country's Middle Belt has taken on a new level of brutality.

At the end of last month, at least 86 people died in the region after violent clashes broke out between farmers and cattle herders, according to police in Plateau state.

Several hundred people are believed to have died this year.

Mr Buhari was not specific about which violence he was blaming on politicians, but he said:

There are pockets of violence in several states some deliberately instigated by disgruntled politicians who have lost all arguments and are desperate to cause mayhem as a way of seeking relevance.

We shall fish them out and punish [them] according to the provision of law."