Xhaka and Shaqiri, who have ethnic Albanian heritage but grew up in Switzerland, put their open hands together with their thumbs locked and fingers outstretched to represent the double-headed eagle displayed on Albania's national flag.

The duo could miss Switzerland's crucial last Group E encounter against Costa Rica in Nizhny Novgorod on Wednesday (June 27) as the alleged offence carries an automatic two-match ban under FIFA's disciplinary rules.

They could be found to be in breach of article 54 of the FIFA disciplinary code, which prohibits acts defined as "provoking the general public".

In an interview with the BBC, Serbian Football Association (FSS) President Slavisa Kokeza condemned the "scandalous and shameful" actions of the two Swiss players.

The build-up to the match had seen exchanges between Serbian players and Shaqiri, who wears boots with the Kosovo flag displayed on one heel and the Swiss one on the other.

"It was not the only provocation by the Swiss players," Kokeza told BBC Sport. 

"One sufficient detail was the football boots of one of their players - the boots had a flag of a non-existing country displayed on them.

"We expect FIFA to impose sanctions against the players who acted against rules of FIFA and fair play, as well as against the national association of the country they play for."

The incidents came after Xhaka scored the opening goal of the game and after Shaqiri netted a dramatic late winner to earn victory over Serbia in Kaliningrad on Friday (June 22).

The nationalist symbol prompted the FSS to lodge an official complaint, prompting FIFA to investigate.

Shaqiri, who plays for Stoke City, was born in Kosovo, the former Serbian province that declared independence in 2008.

Serbia does not recognise Kosovo's independence and relations between the two countries remain tense.

Xhaka's parents are originally from Kosovo and they are of Albanian heritage.

The Arsenal midfielder's father was imprisoned in the former Yugoslavia for campaigning in favour of Kosovan independence.