The Spanish league said it “deplores and condemns the death” of the police officer, and its president said he hopes FIFA and UEFA take action to halt fan violence.
“The Russian ultras shouldn’t have traveled to Bilbao because of their history,” Javier Tebas told the sports daily As.
The trouble erupted ahead of the round-of-32 match in the second-tiered European club competition.
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, and a large police force was deployed to try to prevent fan trouble.
There were reports of other minor clashes involving Russian fans in Bilbao for Thursday’s match.
Six years ago a fan died in Bilbao in clashes after a match between Athletic and German club Schalke.