Russia and football's world governing body FIFA have promised to hold a safe and welcoming World Cup, despite concerns that the tournament could be marred by hooliganism and fan violence.
All violent incidents reported so far have been relatively minor, but a video filmed during Thursday's emotionally-charged match between Argentina and Croatia in Nizhny Novgorod showed a group of men fighting in the stands.
Russia's World Cup organising committee said seven Argentines had been detained by police after the match, in which Croatia beat Argentina 3-0 and left the hopes of the twice world champions hanging by a thread.
The Argentine security ministry said in a statement it had identified four Argentine fans in the video and it will now "ask Russian authorities to immediately detain them so they can be deported."
A spokesman for the Russia-2018 organising committee said: "The matter is now with the judicial authorities to judge the matter in line with the governing laws."
The video, filmed during the match and widely circulated on social media, shows men in Argentina and Croatia team colours kicking and punching each other as onlookers try to break up the fight.
One Croatian supporter is punched and hit repeatedly while lying on the floor and then kicked in the head.
FIFA said earlier on Friday it was working with authorities to identify the people in the video.
"We are absolutely shocked by the images in question. FIFA firmly condemns the behaviour of these so-called fans," a FIFA spokesman said in written comments to Reuters.
"FIFA is cooperating with the relevant security authorities and will do its utmost to contribute to identifying the individuals involved in these criminal acts in order to ensure that they are punished accordingly.
The Croatian Football Federation said it was working to get information about the Croatian fan in the video.
"The Croatian Football Federation is shocked by the video showing an incident at the Nizhny Novgorod stadium," a spokesman told Reuters.
"We always strongly condemn and oppose any sort of fan violence, physical or verbal, and we are obviously very saddened to see a Croatian fan suffering in this video."
The embassies of Argentina and Croatia in Russia and a spokesman for the Argentine Football Association did not respond to requests for comment.
(Reporting by Jack Stubbs; Editing by David Stamp, Mark Potter and Peter Graff)
