The Nigerian military has launched air raids on militant training camps in the north-east of the country, officials say.
An army spokesman said jets and helicopter gunships had been used to attack several camps.
He told the BBC that a plane had been hit by anti-aircraft fire but had managed to return to base.
States of emergency were declared this week in three north-eastern states hit by Boko Haram’s Islamist insurgency.
Nigerian military spokesman Brig Gen Chris Olukolade said two militant bases in the Sambisa Forest Reserve were destroyed in raids.
The reserve is about 70km (45 miles) south of the Borno state capital, Maiduguri, where the militants first emerged in 2009.
Reports say dozens of militants have been killed, but there has been no independent confirmation.
Nigerian forces are trying to regain control in the states of Adamawa, Yobe and Borno.
“It is not just Sambisa, every camp is under attack,” the Reuters news agency quoted Brig Gen Olukolade as saying.
‘Land and air’
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Their mandate is to ensure that activities of Boko Haram insurgents and rebels in these areas are brought to zero level”
Soyinka Okupe Special assistant to the Nigerian president
Meanwhile, explosions and gunfire were heard overnight on Thursday in Katsina state, where gunmen launched several attacks.
Residents told the BBC’s Hausa service that banks, police stations and prisons were destroyed in the town of Daura, near the border with Niger.
They said they had seen the bodies of five members of the security forces and three militants, but there has been no official confirmation of casualties.
Soyinka Okupe, a special assistant to Nigerian President Goodluck Jonathan, said that government forces would continue to hit the militants hard.
“Their mandate is to ensure that activities of Boko Haram insurgents and rebels in these areas are brought to zero level.
“So they will employ everything that is in their power to effect that, including land and air.”
Mobile phone networks were not functioning in many parts of north-east Nigeria on Thursday.
A security official told the AP news agency that the mobile phone service had been shut down during the military operation.
Militants have previously attacked mobile phone masts in the area in an effort to disrupt communications.
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