Bilbao mayor Juan Mari Aburto has threatened to withdraw as a host city for Euro 2020 if UEFA fails to take action against football violence.
A 51-year-old police riot officer died on Thursday from cardiac arrest while on duty after clashes outside Bilbao's San Mames Stadium ahead of the Europa League round-of-32 game between Athletic Bilbao and Spartak Moscow.
"It's necessary that UEFA adopts measures against teams, whoever they may be, so that these disgraceful episodes no longer happen, " Aburto told Cadena Ser radio. "We, in Bilbao, are going to be hosts of Euro 2020 and there are people that are starting to say, 'What, for this?'
"Well no, we don't want to be hosts of Euro 2020 for this. We want to be an open city, do things well and these types of incidents and disgraceful situations require maximum firmness from everyone."
San Mames Stadium and the Aviva Stadium in Dublin were assigned as joint venues for Euro 2020 by UEFA's Executive Committee in December.
The Spanish Football Federation (RFEF) said the Basque police force officer, Inocencio Arias Garcia, suffered a heart attack and died in hospital.
"[Garcia] had collapsed during the intervention that took place when police confronted fans of both teams in the esplanade of the San Mames Stadium, and moments later, there was a flare thrown by a Russian fan close to him," according to the RFEF.
"The RFEF would like to express its strongest condemnation of all types of violent actions by groups of fans who use sporting events in order to provoke incidents and disturbances."
The game was considered "high risk" by local authorities, with a total of 800 officers, including 200 private security hired by Athletic, placed on duty.
"I feel profound sadness because the name of our city has been tarnished, but above all, because a 51-year-old doing his duty has seen his life cut short," Aburto said. "Yes, it was a cardiac arrest, but we cannot forget that he was taking part in a police operation.
"We send our condolences to the family of the police officer and to the police force. We condemn violence -- those groups from either side that make violence part of their lives and that spread hate and clashes wherever they go, this has nothing to do with football."
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.
Police said a Russian man was injured and five people -- three Russian nationals and two Spaniards -- were arrested.
"La Liga profoundly regrets the death of a police officer and condemns violence following the incidents prior to the game between Athletic and Spartak Moscow," the Spanish league said in a statement.
The RFEF has recommended that a minute's silence be observed in all competitions in Spain this weekend.
Information from the Press Association was used in this report.