Oil militants who have slashed Nigeria's petroleum production with attacks on pipelines are calling for a referendum on breaking up the Nigerian federation.

The Niger Delta Avengers group posted a map on social media Sunday suggesting that the West African power house could be split into five countries.

Analysts had predicted that the stunning result of the British referendum to leave the EU would encourage separatists in Nigeria.

The Avengers posted that "President (Muhammadu) Buhari should call for a referendum to enable every Nigerian to vote if they want to stay as Nigerians or not, just like what David Cameron of Great Britain did."

Nigeria suffered a civil war from 1965 to 1970 that killed a million people as the southeastern Igbo people fought to create a separate state of Biafra.