Boko Haram Takfiri militants have killed dozens of civilians during a series of recent violent attacks on four villages in northeast Nigeria's Borno state, local residents and security sources say.

Local residents and the police confirmed on Tuesday that at least 43 people were killed near Monguno, a local government area of Borno State last Friday.

Militants stormed the remote villages in the troubled state and rounded up dozens of people before slitting their throats, media outlets quoted Kilwa village resident Sheriff Kulo as saying.

Sources say the heavily-armed militants also set scores of houses ablaze in the area.

Nigerian police had earlier said that they were investigating reports that dozens of people were killed in a series of raids by Boko Haram extremists in a remote region of northeastern Borno State.

In a separate development on Tuesday, Nigerian President Muhammadu Buhari appointed new military chiefs shortly following the dismissal of the nation’s top military commanders.

The dismissal of entire military top brass was widely expected as Buhari, a former general, had severely criticized the military's poor performance and failure to defeat Boko Haram Takfiri militant group.

Boko Haram has intensified its attacks since Buhari's came into power on May 29. The president has since made crackdown on militants his top priority.

The Boko Haram militancy has left some 15,000 people dead and around 1.5 million others displaced across Nigeria since 2009.

In recent months, the militancy has spilled over into several neighboring African nations as well.

A recent double-bombing attack left at least 14 civilians and three Chadian soldier dead in Cameroon's northern town of Fotokol.

Soldiers from Nigeria, Chad, Cameroon and Niger have been battling Boko Haram terrorists in recent months.

The terrorist group has recently pledged allegiance to the ISIL Takfiri group, which is primarily operating inside Iraq and Syria.