The remains of the 42 fishermen who were kidnapped by Boko Haram last week, at the Nigeria-Cameroon border, have been found in a lake.
The reported stated that villagers near Lake Chad alerted authorities, after several bodies were observed floating. The bodies were removed from the lake on Saturday and Sunday.
The report said fighting between Boko Haram and an insurgency in northern Nigeria has intensified in the past few weeks.
More than 50,000 people have been forced in recent days to flee their homes in southeastern Niger after a series of attacks by Boko Haram.
Niger contributes to a multi-national force set up to fight Boko Haram in the region, where attacks in recent years have killed at least 20,000 people and displaced 2.7 million, according to Amnesty International and the U.N.
The Nigeria-based Islamic militants pledged support for the Islamic State last year.