A military air raid on insurgent camps in northeast Nigeria has killed at least 21 Islamists. The US has warned Nigeria to respect human rights and not harm civilians.
At least 21 people were reportedly killed in Friday's attack in the Sambisa Forest Reserve, south of Maiduguri, the capital of Borno state, a military spokesperson said. There has been no independent confirmation of the number of casualties.
Government troops used jets and helicopters in what has been the military's biggest offensive since Boko Haram revolted four years ago in an attempt to create a separate Islamic state and army.
In a written statement, military spokesperson Brigadeer General Chris Olukolade said soldiers destroyed several camps, heavy weapon stockpiles in forests around Borno state and that the special operations "resulted in the destruction of much of the insurgents' weapons and logistics, such as vehicles, containers, fuel dumps and power generators."
"The Defense Headquarters is quite satisfied with the progress of the operation and the fighting spirit of participating troops," he said.
Olukolade said the death toll would be verified on Saturday.
Three days after President Goodluck Jonathan decreed a state of emergency across three northeastern states, Adamawa, Borno and Yobe, US Secretary of State John Kerry issued a statement saying the US "remained deeply concerned" about the continued fighting in northeastern Nigeria.
"We are also deeply concerned by credible allegations that Nigerian security forces are committing gross human rights violations, which, in turn only escalate violence and fuels extremism," the statement read.
"Washington condemns Boko Haram's campaign of terror in the strongest terms," Kerry said, urging Nigeria to show restraint.
The US is Nigeria's largest foreign investor, notably buying a third of the country's oil.
After Jonathan's decree on Tuesday, the military has taken charge over matters of security across the three states where insurgents have taken control.
Border crossings with Cameroon have been shut down in an attempt to bolster security.
A previous massive deployment of military and police to the region failed to quell violence by Islamist extremists who have killed more than 1,600 people since 2010.
jlw/hc (Reuters, AP, AFP, dpa)