A human rights group says both the Islamist militant group Boko Haram and Nigerian security forces trying to subdue them may have committed crimes against humanity.

U.S.-based Human Rights Watch released a report Thursday saying Boko Haram has committed “widespread and systematic murder and persecution” in its attacks on government agents, Christians, and moderate Muslims.

The report also says Nigeria's government forces have engaged in abuses while fighting Boko Haram, including extrajudicial killings and extended detentions without charge.

Rona Peligal, Africa specialist with Human Rights Watch, says government forces' crackdown on Boko Haram has affected citizens who are not involved in the conflict.

“The government itself has engaged in extrajudicial killings — has engaged in excessive use of force in communities where Boko Haram members might be located. And sometimes these have an impact on the neighboring communities.”

Peligal says the conflict has claimed more than 2,800 lives since 2009, with some 1,300 the result of action by Nigerian security forces.

She says violence escalated this year, with more than 815 killings in the first nine months alone — more than the past two years combined.

Human Rights Watch is calling on the International Criminal Court to examine the actions of all sides.

It calls on Boko Haram to end its attacks, and on Nigerian forces to take “urgent measures” to address human rights abuses that have escalated the conflict.