A police officer died on Thursday in the northern Spanish city of Bilbao in clashes with Spartak Moscow fans ahead of their Europa League soccer game against Athletic Bilbao.
The police 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 teams, police said.
At least five people were arrested.
Spartak won the second leg of the round of 32 tie 2-1 but were knocked out of Europe's second-tier club competition 4-3 on aggregate after losing the first leg 3-1 in Moscow.
Russia hosts the World Cup this year and local authorities are putting strict security procedures in place to control hooligans, including Russian fans who caused trouble at the 2016 European Championship in France and other soccer events.
