At least 20 people were killed in northeastern Nigeria on Sunday in two separate attacks by suspected Boko Haram militants.

Members of the Islamist group attacked Kwajaffa village in Borno state and killed 10 people, Ali Ndume, a federal lawmaker representing the region, said Monday by phone from Maiduguri, the state capital. The attackers burnt down scores of houses, he said.

A separate attack on four villages near Nigeria's border with Cameroon left at least 10 people dead, Asshek Bashir, a resident who fled to Cameroon, said by phone.

"I sneaked out in the night and I'm lucky to have escaped unhurt," he said.

Boko Haram, which means "Western education is sin" in the local Hausa language, has killed more than 13,000 people in its six-year insurgency to impose Shariah, or Islamic law, on Africa's biggest economy. The group has killed at least 1,000 people this year, according to New York-based Human Rights Watch.

Muhammadu Buhari, who won Nigeria's presidential elections last week, pledged in a speech on April 1 to defeat Boko Haram.