Four gunmen started firing indiscriminately at their victims after bursting into a Real Madrid Supporters’ Club based in Baquba around 40 miles north of the capital Baghdad.
The group’s president Ziad Albidani told Spanish sports daily AS the attack happened towards the end of the match before the penalty shoot-out decided by Cristiano Ronaldo.
The number of dead has been put at 12 with eight injured. The extent of their injuries are not known.
The terrorists, believed to be ISIS members, fled and have yet to be captured.
All the victims, said to be aged between 18 and 30, are thought to be Iraqi nationals.
The incident comes just over two weeks after a group of Islamic State terrorists armed with AK-47s attacked the headquarters of a Real Madrid Supporters Club in Balad near Baquba.
Four gunmen started firing at their victims after bursting into a Real Madrid Supporters’ Club
Most of the victims were Real Madrid fans but cafe staff and other customers were also killed with 20 people injured.
Islamic State later claimed responsibility as gruesome pictures and video emerged of the bloodbath.
Real Madrid president Florentino Perez dedicated the club’s Champions League 1-0 victory over Atletico de Madrid to the fans killed in that massacre before news of the latest attack emerged.
He told a Spanish television channel: “I would like to dedicate this cup to our fans in Iraq.”
In a statement in the aftermath of the attack earlier this month, Real Madrid said: “Real Madrid profoundly laments the terrible attack today in Iraq which has ended the life of 16 members of a Madrid fan club and that injured more than 20.