Nigeria declared a state of emergency last weekend after a series of attacks by a radical Muslim sect that killed dozens of people.
The indefinite emergency declaration in four states by President Goodluck Jonathan allows security forces to make arrests without proof and conduct searches without warrants.
The affected areas include parts of the northeastern state of Yobe and the central states of Plateau and Niger, which were all hit by attacks on Christmas Day that left at least 42 people dead.
The attackers targeted churches as well as the state offices of Nigeria's secret police.
A radical sect known as Boko Haram has claimed responsibility for the violence.
The president also declared a state of emergency in parts of the northeastern state of Borno, a stronghold of the feared Islamic sect.
"What began as sectarian crises in the northeastern parts of the country has gradually evolved into terrorist activities in different parts of the country with attendant negative consequences on our national security," Jonathan said.
Nigeria has also closed all international borders near the attack sites.
The U.S. Embassy has warned U.S. citizens to exercise caution in Nigeria.