MOSCOW (REUTERS) - Ukraine supporters have flooded the Facebook page of world football governing body Fifa with over 158,000 comments, most saying "Glory to Ukraine", after it fined Croatia's assistant coach for a video posted on social media in which he used the same slogan.

Fifa hit Ognjen Vukojevic with a 15,000 Swiss Franc (S$20,467) fine and a warning after he and Croatian defender Domagoj Vida said, "Glory to Ukraine" in a video that went viral after Croatia beat Russia in a World Cup quarter-final on Saturday (July 7).

Both men have played for Ukrainian club Dynamo Kiev.

Croatia's Football Federation later sacked Vukojevic from the national team's coaching staff.

Relations between Ukraine and Russia remain highly charged following Moscow's 2014 annexation of Ukraine's Crimea region and its backing for a separatist rebellion in eastern Ukraine.

Some Ukrainian politicians have called on countries to boycott the World Cup, which Russia is hosting.

By Tuesday afternoon, Fifa's Facebook page had over 157,000 reviews from users giving it the lowest one-star rating, most less than 48 hours old and including the phrases, "Glory to Ukraine!", "Glory to Croatia!" and "Shame on Fifa!"

Fifa did not immediately comment on the posts.

"Support for Russia means support for annexation and military aggression. Shame on you!" posted a user who gave his name as Vadim Ermilow from Ukraine's capital Kiev.

"Please answer my question: Why can a football player not express his attitude towards what is going on in the world?" asked Oleg Nazarov from the city of Kremenchuk.

The Ukrainian national team did not qualify for the World Cup.

The country's football authority and some Ukrainian politicians have voiced support for Vukojevic, who Fifa said on Monday had apologised for his actions.

"'Glory to Ukraine' is a commonly used greeting in Ukraine... (and) should not be interpreted as an act of aggression or provocation," the Football Federation of Ukraine said in a statement on Sunday.

Croatia face England in the World Cup semi-finals in Moscow on Wednesday.