"Disciplinary proceedings have been opened against the Croatian Football Federation (HNS)," the governing body of football in Europe said in a brief press release on Monday.
The incident was described as racist behaviour under Article 14 of the UEFA Disciplinary Regulations (DR) and proceedings were also launched for "Improper conduct of the team" (5 cards or more) under Article 15 (4) DR.
The HNS can expect a fine as well as some other measures, including suspension of the national team.
After a large sign very much resembling swastika appeared to have been mowed into the turf before at the Poljud Stadium, HNS spokesman Tomislav Pacak told the press on Friday evening this was sabotage and a felony, adding that the HNS expected police to identify the perpetrators.
At first, it was unclear whether the symbol was mowed into the pitch or painted on the grass, but it was clearly marked in the middle of the half Italy were attacking in the first period.
This is a disgrace not just for the HNS but for the whole of Croatia, Pacak said.
"As far as we have learned, the symbol was imprinted into the pitch between 24 and 48 hours before the match so that it could be visible during the game," added Pacak.
The HNS press officer Pacak gave an official statement in which he apologized to "all viewers, our guests from Italy and the players from both teams, for the Nazi symbol on the Poljud Stadium grass."
"Technically speaking, a chemical agent was used on the field 24 to 48 hours before the kick-off, timed to be visible during the qualifying match. During the halftime, we have tried to remedy the situation to the best of our abilities, given the short amount of time," according to Pacek's press release sent to media outlets on Friday evening.
The Croatian federation immediately notified UEFA of the incident.
The match in Split was played behind closed doors as punishment for racist chanting and crowd trouble by Croatia fans, which temporarily halted the November match between the two sides at San Siro.
The HNS president Davor Suker on Saturday condemned the incident.
I hope that hooligans will not succeed and we insist on the protection of the Croatian national team, the HNS, the City of Split and Croatia as well as football against hooliganism, the outraged Suker said at an extraordinary news conference in the biggest Croatian coastal city.
The police are probing the incident and have pressed charges against unidentified perpetrators.
Croatia's President Kolinda Grabar Kitarovic and government on Saturday joined in the condemnation of the incident.