Nigeria has suspended activities of UN children's agency (Unicef) in the north-east part of the country accusing it of spying for Islamist militants operating in the area.

"[Unicef staff] train and deploy spies who support the insurgents and their sympathisers," the Nigerian military said in a statement.

These were "unwholesome practices that could further jeopardise the fight against terrorism and insurgency," it added.

The army said that Unicef had abdicated its role to look after children's well being and was instead engaged in undermining the army's counter-terrorism operations.

It accused Unicef of "spurious and unconfirmed allegations... on alleged violations of human rights by the military".

The news of the suspension has come as a surprise to many, including the organisation itself, which told the BBC it was verifying the information.

The north-east has been riven by a decade-long insurgency by Boko Haram and its splinter group Islamic State West Africa, in which more than 30,000 people have been killed and many more driven from their homes.

Aid organisations provide food and care to millions of people displaced by the fighting.