Nigeria's army has acknowledged for the first time that soldiers were killed in a militant attack last Sunday on a base in Borno state, in the north-east.

It had been reported that at least 40 soldiers died when an Islamist militant group targeted the base in Metele.

The army disputes that death toll but has not given its own figure.

With just three months to go to presidential elections, the authorities are keen to show they have the security situation under control.

President Muhammadu Buhari, who is running for a second term, came to power in 2015 after promising to defeat Boko Haram militants.

The insurgents, who have caused havoc in Nigeria through a wave of attacks, are fighting to overthrow the government and create an Islamic state.

'Trying times'
While the army has retaken most of the territory the militants once controlled, they are still able to carry out deadly attacks.

In a statement, released on Friday evening, the army admits that it is operating in "trying times", which is a rare if veiled admission that the military is experiencing serious setbacks in the fight against the jihadists, says BBC Africa editor Will Ross.

It added that "false casualty figures" and the sharing of inaccurate videos boost the "propaganda intent of the terrorists".

Reports of the deaths at the camp vary.

Reuters news agency quoted an army officer as saying earlier this week: "The insurgents took us unawares. We lost about 100 soldiers. It is a huge loss."

On Monday, a Boko Haram faction loyal to the Islamic State group, known as the Islamic State West Africa Province, said it had carried out the attack and put the death toll at at least 40.

President Buhari's political opponents in the Senate said 44 soldiers had died.