Lagos, Nigeria (CNN) -- At least 20 insurgents were killed Friday as Nigeria's military carried out an aerial bombardment of suspected militant Islamist camps in the country's northeast, a Defense Ministry spokesman said.
The raid by Nigerian Air Force jets and attack helicopters is part of what the military says is a "massive deployment" of forces this week to tackle insurgent groups, including Boko Haram.
"Our military has overrun a number of the militants' camps in north and central Borno state," said defense spokesman Brig. Gen. Chris Olukolade.
"Within those insurgents' camps, we discovered that they have been storing sophisticated, high-caliber weapons including anti-tank and anti-aircraft weapons."
Asked whether the military had inflicted any casualties on the insurgents, Olukolade said, "definitely so. Conservatively speaking, over 20 dead so far."
Members of the armed forces have suffered only minor injuries, according to Olukolade.
"The operation continues, we are injecting even more troops and resources into those areas," he added.
The military operation was announced Wednesday, a day after President Goodluck Jonathan declared a state of emergency in Borno, Yobe and Adamawa states.
The president blamed "terrorists" aimed at "rebellion," causing "fear among our citizens and a near breakdown of law and order in parts of the country."
He also noted a rise of insurgent violence in eight other states, including Nasarawa, where scores of police officers were killed last week.
"Insurgents and terrorists," including Boko Haram, are trying to destabilize Nigeria, Jonathan said.
"The military operation will focus on tracking down criminal elements within the vicinity of border communities prone to terrorist activities," Olukolade said Wednesday.
He did not confirm the number of troops deployed or which units are involved in the military operation.
Much violence over recent years has been blamed on Boko Haram, the name of which means "Western education is sacrilege."
On Friday, a spokesman for the U.N. human rights commissioner told reporters that Boko Haram could face war crimes charges for alleged ethnic and religious cleansing in Nigeria.
Addressing reporters in Geneva, Rupert Colville urged it and other extremist groups to stop "cowardly attacks" against civilians, security forces, Nigerian officials and foreign nationals.
According to Human Rights Watch, the group has killed more than 2,800 people in an escalating campaign to impose strict Islamic law on largely Muslim northern Nigeria.
The U.N. human rights office is calling on Nigeria's government to respect human rights principles during security sweeps, following reports of heavy casualties in some parts of the country.
Nigeria is Africa's most populous country, with a population of nearly 175 million according to the CIA World Factbook, and is the political and economic powerhouse of West Africa.
CNN's Laura Smith-Spark and Greg Botelho contributed to this report.