A Nigerian military court on Wednesday sentenced 54 soldiers to death for mutiny after they refused to deploy for an operation against Boko Haram Islamists in the northeast, their lawyer said.

"They sentenced 54 to death and acquitted five," said prominent human rights lawyer Femi Falana, following a court martial that began on October 15 and was conducted behind closed doors.

Reporters were turned away from the court before the tribunal gave its verdict and military officials were not available for comment afterwards.

In a similar case in September, 12 soldiers were sentenced to death for mutiny after firing on their commanding officer in the northeast city of Maiduguri, where troops are battling against Boko Haram.

Both sentences are subject to approval by top army brass, but there has so far been no indication that senior officers oppose the rulings.

- Lack of weapons -

Frontline troops have consistently complained that they lack the weapons and other supplies needed to face Boko Haram in insurgent strongholds.

The Islamists, waging a five-year uprising to create a caliphate in northern Nigeria, are known to have tanks, rocket propelled grenade launchers and other heavy weaponry, while troops have reported lacking ammunition for basic assault rifles.

After Boko Haram captured a series of towns in the northeast earlier this year, the military vowed to retake all lost territory.

The 7 Division, based in Maiduguri, was tasked with leading the offensive but there are numerous reports of troops refusing to deploy.

Wives of soldiers have staged protests outside a military base, trying to stop their husbands from heading to conflict areas without proper equipment.

Soldiers have also carried out similar demonstrations, including one group that set up a protest camp on the outskirts of Maiduguri.

The men sentenced to death on Wednesday were part of the special forces division ordered in August to retake three lost towns in restive Borno state, of which Maiduguri is the capital.

Defence officials insist that troops are properly equipped, but President Goodluck Jonathan earlier this year sought permission from lawmakers to secure a $1 billion foreign loan to upgrade the military.

The request was seen as a tacit acknowledgement from Jonathan that Nigeria's soldiers were being out-matched.

Boko Haram, blamed for more than 13,000 deaths since 2009, is believed to control more than two dozen towns and villages in the northeast.

While the military has claimed a series of victories in recent weeks, large swathes of territory remain in rebel hands.