Boko Haram has claimed responsibility for the mass killings in the north-east Nigerian town of Baga in a video where he warned the massacre “was just the tip of the iceberg”.
As many as 2,000 civilians were killed and 3,700 homes and business were destroyed in the 3 January attack on the town near Nigeria's border with Cameroon, according to estimates by Amnesty International.
Nigeria's government has disputed this figure and put the actual death toll at 150.
In a video released on Tuesday, leader Abubakar Shekau said killings had been committed as Allah "commanded us in his book", according to a translation from Arabic provided by the SITE Intelligence Group.
"This is just the beginning of the killings. What you've just witnessed is a tip of the iceberg. More deaths are coming," he warned.
The message came as regional foreign ministers met in Niger to negotiate how to establish a multinational force to fight the extremists.
Shekau's message added that "this will mark the end of politics and democracy in Nigeria," as the country gears up for critical presidential elections.
The attack on Baga sparked international outrage not seen since Boko Haram kidnapped nearly 300 girls from a boarding school in April last year. Nigeria's demoralised and ill-equipped military has failed to rescue the 219 who remain in captivity.
Neighbouring Cameroon has had more success in combating Boko Haram, this month retaking a seized military base and winning freedom for scores of abducted women and children.
Additional reporting by agencies