Nigerian President Goodluck Jonathan says radical Islamist sect Boko Haram has infiltrated the government, complicating efforts to fight the group.

At a speech Sunday in the capital, Abuja, Mr. Jonathan asserted that Boko Haram members are in the executive, parliamentary and judicial branches of government, and the armed forces.

He said the situation is even worse than it was during Nigeria's civil war in the late 1960s because of the difficulty in telling who is a Boko Haram member.

Meanwhile, police say the militant group Monday killed a secret police officer in northeastern Nigeria. Borno state police commissioner said the gunmen attacked the officer of the State Security Service as he left a mosque.

The shadowy militant group has claimed responsibility for several deadly attacks, including the Christmas Day bombing of a church near Abuja that killed more than 30 people. Authorities blame dozens of other shootings and bombings on the sect.

President Jonathan recently declared a state of emergency in 15 locations across northern Nigeria as part of a campaign to subdue the group, which is fighting for wider implementation of Islamic law.

U.S. State Department spokeswoman Victoria Nuland Monday condemned the violence, saying “extremist groups like Boko Haram” are trying to play on the religious tensions in Nigeria to “try to rip the country apart.”

The president has also deployed extra troops to the north. Despite the measures, gunmen killed at least 20 people Friday in Adamawa state, near Cameroon. A purported Boko Haram spokesman claimed responsibility.

Last week, the same spokesman, known as Abu Qaqa, warned Christians to leave the Muslim-majority north.