The International Criminal Court's prosecutor Fatou Bensouda on Friday said she has enough evidence to open a full investigation into atrocities in Nigeria.

In a statement on Friday, Bensouda said the decade-long preliminary examination pointed towards crimes against humanity and war crimes committed by armed group Boko Haram and the Nigerian security forces.

"Moving forward, the next step will be to request authorization from the Judges of the Pre-Trial Chamber of the Court to open investigations," she said.

"As we look ahead to future investigations in the independent and impartial exercise of our mandate, I also look forward to a constructive and collaborative exchange with the Government of Nigeria to determine how justice may best be served under the shared framework of complementary domestic and international action."

Bensouda noted that the preliminary examination, which started in 2010, took that long "due to the priority given by my Office in supporting the Nigerian authorities in investigating and prosecuting these crimes domestically."

Nigeria has been dogged by Islamist violence for more than a decade, killing tens of thousands and displacing millions others.

Following Bensouda's statement on Friday, Amnesty International welcomed the prospect of a full investigation, saying it was long overdue.

"After years of calling on the ICC Prosecutor to open a full investigation, this is the first meaningful step towards justice that we have seen for victims of atrocious crimes committed by all parties to the conflict in Northeast Nigeria," said Netsanet Belay, Amnesty's Director of Research and Advocacy.