Four people have been arrested and questioned in Spain on suspicion of conducting an online hate campaign encouraging fans to racially abuse Real Madrid star forward Vinicius Jr, police said on Thursday.
The men were detained on 14 and 15 October then released as investigations continued into social media slogans which urged fans to wear face masks so they could insult the black Brazil international without being identified, police added.
They were the first detentions announced by police linked to the campaign, which set out to target the 24-year-old in the build-up to the Spanish capital's derby on 29 September at Atletico Madrid's Metropolitano stadium. It used the hashtag #MetropolitanoConMascarilla (Metropolitano with a Mask).
Vinicius Jr, who has faced abuse at a number of matches, last year called LaLiga and Spain racist after receiving slurs from the stands during a match at Valencia's Mestalla stadium.
In a landmark case, three Valencia football fans were each sentenced to eight months in prison in June for hate crimes against Vinicius Jr - the first conviction for racist insults in a soccer stadium in Spain.
On Thursday, Spain's National Police did not name the four men and there was no immediate statement from any lawyers representing them.
Under Spanish legal procedures, a judge will investigate and eventually consider whether there is enough evidence to proceed to trial.
Police said the online campaign went viral, raising "significant social alarm". The investigation remains open and could lead to more arrests, the force added.
DERBY INCIDENTS
LaLiga stepped in the day before the clash, saying it was calling for the arrest of anyone involved in the campaign that it said amounted to the crime of incitement to hatred.
There were no major incidents of racial abuse reported at that match but the derby against Real Madrid was suspended for several minutes due to items being thrown onto the pitch.
On Thursday, the prosecutor office in Madrid opened a criminal investigation to identify those fans who threw objects at Real Madrid's goalkeeper, Thibaut Courtois, who was previously an Atletico player.
The Spanish soccer federation RFEF ordered Atletico to play last weekend's 3-1 win over Leganes with a partial stadium closure over the incidents.
Atletico could face another penalty for the Madrid derby incidents from the government's Anti-Violence Committee, which has called for a two-week total closure of the Metropolitano Stadium plus a €65 000 fine.
Following the derby incidents, LaLiga submitted a report to Spain's Commission Against Violence listing 142 alleged incidents related to Atletico's Frente Atletico "ultras", as hard-right fans are known, dating back to 2015.
LaLiga added it would file a criminal complaint and called for a ban on the Frente Atletico.
Atletico Madrid did not immediately reply to a request for comment but they said earlier this month they were committed to adopt internal disciplinary measures against their associates involved in racist, xenophobic or intolerant incidents.
Atletico also decided last week not to sell tickets to some of their supporters for the team's next five away games in all competitions.