FIFA has charged the Irish Football Association (FAI) over a shirt logo worn in March to commemorate the 100th anniversary of an uprising against British rule.
"We can confirm that disciplinary proceedings have been opened on this matter," a spokeswoman for world soccer's governing body, whose rules forbid players from wearing anything that can be perceived as a political statement, said on Friday.
"We cannot comment further at this stage nor speculate on any outcome."
There was no immediate reaction from the FAI.
Ireland's players wore the logo -- with the words Eire 1916/Ireland 2016 -- when they played a friendly match against Switzerland on March 25, two days before official state commemorations of the 1916 Easter uprising.
The rebellion is widely seen as the defining moment of an independence struggle that ended centuries of British rule five years later.
But many unionists in the British province of Northern Ireland consider the event an illegal uprising. The province's First Minister Arlene Foster has said it was used to justify Irish Republican Army violence in the 1970s and 80s.
FIFA is separately involved in an argument with England and Scotland, who want their players to wear poppies on armbands when they play a World Cup qualifier on Nov. 11, the anniversary of World War One's Armistice Day in 1918.
Irish media said the Ireland logo had been used as an example by England and Scotland in negotiations with FIFA.
British Prime Minister Theresa May strongly criticised FIFA on Wednesday, telling parliament that the soccer body's stance was "utterly outrageous".
"Our football players want to recognise and respect those who have given their lives for our safety and security. I think it is absolutely right that they should be able to do so," she said.
FIFA is trying to recover from the worst graft scandal in its history which has seen 42 people, including former FIFA executive committee members, indicted in the United States since May last year.
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