Nigerian authorities relaxed a curfew and intensified military patrols in Maiduguri on Tuesday, a day after suspected Islamist militants launched strikes on military bases in the northeast city.
Gunmen stormed the air force base and several other military locations in an apparently coordinated attack in the early hours of Monday, the military and local residents said. It was not clear how many casualties there were.
The attack ended weeks of relative calm in the capital of Borno state, the birthplace of the Boko Haram insurgency that is the gravest threat to security in Africa's top oil producer and the continent's second largest economy.
Thousands of people have been killed this year alone in violence linked to Boko Haram, an Islamist sect which wants to impose sharia law in a country of nearly 170 million people split roughly equally between Christians and Muslims.
Baba Ahmed Jidda, a spokesman for the government of Borno State, of which Maiduguri is the capital, said on Tuesday the curfew had been relaxed to between 7pm and 6am, from the 24-hour restriction imposed on Monday.
In May, President Goodluck Jonathan declared a state of emergency in Borno and two other states, ordering an all-out offensive against the Islamist group.
Initially the offensive appeared to temper the insurgency as soldiers wrested back control of towns, cities and stretches of semi-desert in the northeast from the militants.
But Boko Haram's fighters have survived many assaults during their 4-1/2-year-old insurgency and proven adept at retreating to remote areas, including forested hills and semi-arid scrubland, before launching guerrilla counter strikes.