A Spanish police officer has died after security forces clashed with fans of the Russian soccer club Spartak Moscow in the Spanish city of Bilbao, which was hosting a Europa League match.
The incident late on February 22 raised concerns less than four months before Russia is set to host the World Cup.
Basque authorities in northern Spain said the riot police officer died apparently of cardiac arrest in a hospital after police clashed with fans outside San Mames Stadium in Bilbao, where a match was taking place between Athletic Bilbao and Spartak.
Police said a Russian man was injured in the incident and five people were arrested — three Russian nationals and two Spaniards.
The identity of the dead officer was not immediately disclosed. Local media said he was 50 years old.
There were conflicting reports about what caused his death, with some saying he took ill during the confrontations and other reports suggesting he was hit by an object during the fighting.
Spanish authorities said an autopsy would be performed to determine the exact cause of death, but they said preliminary indications are that the death did not result from violent contact.
Earlier on February 22, German police arrested a Russian suspected of seriously injuring a English soccer fan during the European Championship in France two years ago.
The governing body for European soccer said it "strongly condemns the violent clashes which occurred in Bilbao" and said it was seeking further information from Spanish authorities about the incident.
The Spanish league said it "deplores and condemns the death" of the police officer, and its president said he hoped the world and European soccer governing bodies would take action to halt fan violence.
"The Russian ultras shouldn't have traveled to Bilbao because of their history," league president Javier Tebas told the sports daily As, using a term for hardcore fans with a reputation for extreme behavior.
The trouble started ahead of the European club match in Bilbao.
Police were escorting some Spartak fans into the stadium, but a stray group allegedly started igniting fireworks and throwing flares and objects toward Athletic supporters and police officers.
The fighting spread onto the streets near the stadium and police struggled to restore order. Many fans were seen trying to run away from the trouble as fireworks exploded all around.
There was concern ahead of the match because of the reported presence of 'Ultra' Russian fans in Bilbao. Spanish authorities said more than 500 police were deployed to try to prevent fan trouble.
There were reports of other minor clashes involving Russian fans who traveled to Bilbao to attend the match.
Six years ago, a fan died in Bilbao in clashes after a match between Athletic and the German club Schalke.
With reporting by AP and AFP