Argentina players criticised for holding up political banner relating to Falklands war
FIFA's Stadium Code of Conduct bans "banners, flags, flyers, apparel and other paraphernalia that are of a political, offensive, and/or discriminatory nature" inside stadiums.
World soccer's ruling body did not immediately reply to a request for comment. British business minister Peter Kyle said the incident must be formally investigated, stressing that politics must be kept separate from the World Cup.
"I'm really proud of our team ... the dignity that they showed, and that was in real contrast to what we saw with the Argentine team last night," Kyle told BBC Radio on Thursday. "I really do hope that FIFA do a proper investigation into it."
The question of sovereignty over the islands in the South Atlantic, known to the British as the Falklands and the Argentines as the Malvinas, has been a long-running sore in relations between the countries.
They fought a short conflict over the islands in 1982, in which 649 Argentine soldiers and 255 British combatants died. Britain ultimately retained control of the islands, and the vast majority of residents have said they wish to remain part of Britain.
But Argentina has long argued that it inherited the islands from Spain after its independence in 1816, and that Britain took control in 1833 through an illegal colonial act.
Lisandro Martinez and Giovani Lo Celso held up the banner, grinning, and waved to fans in the stands. It was unclear where the banner had come from.
It is not the first time the question of political banners has come up during this World Cup. Last month in Los Angeles, Iranian-Americans waved pre-revolutionary flags that are symbols of protest against the Tehran government when Iran played. Those matches proceeded without incident.