Amnesty International has said that Nigeria's military top brass were warned of Boko Haram attacks on the northeast towns of Baga and Monguno this month but failed to take action.
The January 3 massacre in Baga reportedly killed hundreds of people, if not more, and destroyed thousands of homes, while the takeover of Monguno last weekend was seen as a major setback for the security forces.
The UK-based human-rights organisation said on Wednesday that it received information from senior military officers and other sources indicating that defence officials were told about Boko Haram's plans to attack both towns but did not act on requests to send reinforcements.
"It is clear from this evidence that Nigeria's military leadership woefully and repeatedly failed in their duty to protect civilians of Baga and Monguno despite repeated warnings about an impending threat posed by Boko Haram," Netsanet Belay, Amnesty International's Africa director, said.
Regarding Baga, Amnesty International said troops in the town in the north of Borno state reported a build-up of fighters in the area before the attack.
Rebels also warned civilians about an impending strike and several hundred residents consequently fled, the group added, citing military and local sources.
A Monguno resident was quoted as saying that residents there were also warned about a looming Boko Haram offensive and that this information was passed on to the military but no action was taken.
In a statement, Chris Olukolade, Nigerian government's defence spokesperson, said the Amnesty International's statement was "misleading".
"The misleading conclusions by Amnesty International could have been avoided if they had made meaningful efforts to verify the inciting allegations," he said.
It said that Amnesty International's effort to use the activities of the fighters to find fault with the military's "counterterrorism operations ... is inaccurate and unfair".
The military has repeatedly described Amnesty International as an unreliable organisation with a political agenda.
Amnesty International made similar accusations concerning an April 14 attack in Chibok, also in Borno, which saw Boko Haram kidnap more than 200 schoolgirls, causing global outrage.
Rights groups and prominent leaders across Nigeria have widely criticised the security services for their handling of the Boko Haram campaign.
Civilians have repeatedly been left defenceless in the face of attacks and President Goodluck Jonathan, who is standing for re-election in less than three weeks, has so far not delivered on promises to contain the violence.