The International Red Cross and Red Crescent Movement (ICRC) says at least 76 people were killed when an air strike by a Nigerian Air Force plane struck a refugee camp on January 17.
The casualty toll announced by the ICRC on January 18 was at least 24 deaths higher than initial reports after the air strike.
Nigeria's military said the air strike at Rann in Nigeria's Borno state was a mistake and that the civilians were accidentally killed.
It said the air strike was meant to target the Boko Haram Islamic extremist group, which has been battling government forces in Borno for seven years in an attempt to create an Islamic caliphate in northeastern Nigeria.
The ICRC said six Nigerian Red Cross workers were among those killed and that 13 of its staff were among at least 113 people wounded.