ABUJA - Nigerian President Goodluck Jonathan declared a state of emergency in three northeastern states on Tuesday, ordering in more troops to try to stem an increasingly violent Islamist insurgency.

Islamist sect Boko Haram has intensified its attacks on security forces and government targets in its northeast stronghold this month, prompting Jonathan to declare an emergency in Borno, Yobe and Adamawa states.

"We are facing ... a rebellion and insurgency by terrorist groups which pose a very serious threat to our national unity," Jonathan said in a televised address.

"They have attacked government buildings and facilities. They have murdered innocent citizens and state officials. They have set houses ablaze, and taken women and children as hostages. These actions amount to a declaration of war."

His orders followed growing evidence that Boko Haram now control parts of the northeastern territory around Lake Chad, where local government officials have fled.

Security officials say they control at least 10 local government areas of northeastern Borno state, the epi-centre of the insurgency.

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