“Dead bodies were found in houses, streets and many more in the Damasak River which has dried up,” said local man Kaumi Kusur, adding the victims were buried in 20 mass graves at the weekend.

Mohammed Sadiq, another local who helped in the burials on Saturday, put the death toll at more than 400 but the Borno state government did not state a precise figure, giving a toll of “hundreds”.

Troops from Chad and Niger retook Damasak from Boko Haram on March 9 as part of a regional offensive to combat the militants, who captured the town in November last year.

A Chadian security source said at the time that some 200 rebel fighters were killed in the offensive as well as 10 soldiers.

On March 20, Chadian army spokesman Colonel Azem Bermandoa Agouna said about 100 bodies were found in a mass grave under a bridge just outside Damasak. Some had been decapitated while others shot.

Agouna estimated that the massacre probably occurred in January.