A senior commander of the militant Islamist group Boko Haram was arrested Saturday, two Nigerian security sources said.
The Nigeria Joint Task Force, which led the operation, declined to name the commander on record.
"We are all afraid of the Boko Haram -- even we --security officials. People don't want us to say anything about Boko Haram for the fear that they will be killed," said one of the sources, who asked to remain anonymous because he was not authorized to talk to the media and because he fears retaliation.
The source said the commander was arrested at a senator's house in the northeastern city of Maiduguri early Saturday afternoon.
A second security source confirmed the arrest of a senior Boko Haram commander, but declined to provide any details.
Boko Haram, whose name means "Western education is forbidden," is fighting to impose a strict version of Sharia law in the northern of the country. The group has referred to itself as the "Nigerian Taliban."
Nigeria has almost equal numbers of Christian and Muslims, with the south predominantly Christian. Boko Haram and other Muslim groups claim the north has been starved of resources and marginalized by the government of Goodluck Jonathan, who is a Christian.
From its base in Muslim-dominated northern Nigeria, Boko Haram has waged a violent campaign of bombings of Christian churches that have killed hundreds and wounded many more. There have been fewer attacks by Christian militant groups.
U.S. officials have expressed concerns that Boko Haram is beginning to cooperate with al Qaeda in the Islamic Maghreb and another al Qaeda-linked group in Somalia to target American interests in Africa.