A riot police officer has died after violent clashes involving Spartak Moscow and Athletic Bilbao fans broke out in the streets before their Europa League game on Thursday night.
At least five people were arrested after fireworks, flares and glasses were thrown between supporters in Bilbao in violent scenes that hospitalised several others.
One police officer died in hospital after suffering a heart attack.
The officer took a blow to the face before suffering cardiac arrest.
A spokesman for the Basque police said: 'We can confirm this death' - but refused to add any further comment on the cause of death.
The officer died in hospital, where he had been taken following a heart attack when the regional Basque Country police force Ertzaintza was trying to stop street battles between supporters of the two teams, the police said.
In a statement, UEFA said: 'UEFA strongly condemns the violent clashes which occurred in Bilbao on Thursday night.
'We are in contact with local authorities to obtain further information on these incidents. UEFA sends its sincere condolences to the family and colleagues of the police officer who passed away.'
