Satellite images reveal that 2,275 homes were destroyed during a military raid to hunt down militant Islamists in the northern Nigerian town of Baga last month, a rights group has said.
Human Rights Watch said soldiers “engaged more in destruction than in protection” after Boko Haram fighters attacked a military patrol.
The army has not commented on the latest allegations.
It has said 37 people were killed; others say more than 180 died.
The Islamist Boko Haram group has waged an insurgency to create an Islamic state since 2010.
Correspondents say soldiers have often been accused of using excessive force in its efforts to put down the insurgency.
‘Duty of protection’
Human Rights Watch (HRW) has called on the Nigerian authorities to impartially investigate and prosecute soldiers responsible for recent violence in Baga.
It said satellite images it had analysed undermined the military’s assertion that only 30 houses were destroyed during the fighting in Baga, a remote fishing community on the shores of Lake Chad, on 16 and 17 April.
Baga residents told HRW that soldiers ransacked the town after Boko Haram killed a soldier during an attack on a military patrol.
Maina Ma’aji Lawan, a senator for the area, told the BBC Hausa service that more than 4,000 houses had been burnt and more than 200 people had died.
Community leaders told HRW that 2,000 burned homes had been counted and 183 bodies identified after the military raid ended.
Satellite images corroborated this account and had identified 2,275 destroyed buildings with another 125 severely damaged, the US-based rights group said.
“The Nigerian military has a duty to protect itself and the population from Boko Haram attacks, but the evidence indicates that it engaged more in destruction than in protection,” Daniel Bekele, Africa director at Human Rights Watch, said in a statement.
The BBC’s Nigeria correspondent Will Ross says the area is a stronghold of Boko Haram and one eyewitness said prior to the violence that soldiers had accused residents of sheltering the militants.
In the week after the conflict in Baga, the troop commander in Baga, Brig Gen Austin Edokpaye, denied media reports that hundreds of houses had been burnt.
He said “explosions from Boko Haram terrorists'” set the thatched houses ablaze.
Thirty militants, one soldier and six civilians died, the army said.
Rocket-propelled grenades and bomb-making material had been recovered in the raid, a military statement said.