Seven fans were confirmed dead and many injured as an electric cable from a high tension installation fell on the viewing centre where they were watching the match between Manchester United and Anderlecht.
“FIFA is deeply saddened by the deaths of several football fans in Calabar and offer our deepest condolences to family and friends of the victims,” the world football body wrote on its Twitter handle on Friday.
The News Agency of Nigeria (NAN) reports that Manchester United has also commiserated with the families of the dead fans.
United won the game 2-1 and qualified for the semi-finals of the competition.
United will face Spanish side, Celta Vigo, in the semi-finals, while Ajax of Netherlands will meet Lyon of France.