A Spanish police officer has died after violent clashes between Athletic Bilbao and Spartak Moscow supporters took place in Spain on Thursday night.

The two sets of fans clashed ahead of Thursday's Europa League last-32 second leg at Bilbao's San Mames stadium.

The police officer, who has been named as 51-year-old Inocencio Alonso Garcia from the Basque County's police force, is believed to have suffered a heart attack while intervening in the ugly scenes involving both sets of supporters.

Footage online has emerged of fireworks being thrown during the street clashes, with police, who are believed to have made five arrests, claiming that a number of people had arrived with batons and knives.

Spartak Moscow won the second leg of their last-32 clash 2-1, but Bilbao went through 4-3 on aggregate.