The order last night follows a car bombing at a busy security checkpoint on Thursday that killed at least 19 people and wounded 66 in Abuja, the capital. The blast was near the site of an April 14 explosion that killed 75 people.
Abuja is hosting the World Economic Forum on Africa May 7-9 with international personalities, business and African leaders. Chinese Premier Li Keqiang is guest of honour.
The bombings were blamed on the Islamic extremist Boko Haram terrorist network that has attacked schools and slaughtered hundreds of students.