Giannakopoulos was handed a 12-month ban by the league's disciplinary judge, who ruled his public statements had threatened to endanger "duly harmonious relationships among clubs and were detrimental to the sport of basketball".

The ban will prevent Giannakopoulos from accessing arenas where Euroleague Basketball competitions are being played.

He was sanctioned due to alleged inflammatory comments made about rival fans of Turkish club Fenerbache on Instagram, which he later deleted.

"All Euroleague Basketball members, due to being public personalities, hold an enormous influence on fans and youth which must be exercised with the greatest responsibility," Euroleague Basketball wrote in a statement when disciplinary proceedings were opened.

"Despite understanding that rivalry and competition are at the centre of the European sports culture, competition organisations and governing bodies need to lead by example and always actively promote that these are understood within a framework of respect and good manners, ensuring that sport remains a bridge to unite people through passion, rather than to provoke confrontation.

"Euroleague Basketball believes that the latest statements made by Mr. Giannakopoulos in his official Instagram account are of a maximum severity and they create serious damage to the image and reputation of the league and of all its clubs, including his own club, Panathinaikos Athens.

"The club has earned an elite international reputation over recent decades based on its performance on the court.

"That reputation should not be overshadowed by such unseemly behaviour from one individual, which is completely opposite to the values that the club and the league stand for."

Giannakopoulos defended his comments in a statement, claiming they had been made after he received "threats and insults, both to myself and to my family by thousands of Turkish nationals".

He threatened to pull the team our of the Euroleague should the sanction not be lifted, stating that a referendum would be organised for fans to vote.

An appeal against the ban was dismissed on February 8, leading to the club stating a referendum would be held in the coming days.

"That is why Panathinaikos immediately starts the actions so that the Panathinaikos world, after being informed of all the details, decides on the future of the team in the organisation, through a referendum, which will be held in the next few days," a Panathinaikos statement said.

"The result of the referendum will be directly applicable."

Giannakopoulos had stated that if the fans opted to remain in the Euroleague, he would leave the organisation.

Should the fans vote to leave, he claimed they would participate in another European event.

However, following their win over Baskonia Vitoria Gasteiz, Giannakopoulos hinted at a change of heart and suggested a vote would not take place, after fans showed their support to him during the match.

The players did not line up for the Euroleague anthem.

Euroleague's chief executive Jordi Bertomeu expressed his hope a solution could be reached.

"Firstly, I must say that Euroleague clubs need Panathinaikos," Bertomeu said, according to Eurohoops.

"Secondly, Panathinaikos needs Euroleague clubs, as well.

"And thirdly, we cannot accept disrespectful insults towards Euroleague as an organisation.

"Panathinaikos is one of the most successful clubs in European basketball history, they have many accomplishments and titles.

"Unfortunately, we are having some problems with the owner of the club but I believe that we are going to get to the point where we will return to normal, as soon as possible."

Panathinaikos have a 10-year contract to participate in Euroleague, but have an opt-out clause of €10 million (£9 million/$12 million).

The threat to leave Euroleague could result in the club moving to the rival International Basketball Federation Europe Champions League.

The FIBA Europe Champions League tournament has been the source of a dispute between the organisation and Euroleague, with both clashing over ownership of the European club game.

The FIBA Champions League is designed to replace the Euroleague as the top level competition on the continent.

Should Panathinaikos fans opt to depart the Euroleague, it would be a major blow to the competition, with the Greek team the fourth most successful in the competition.

They have won the Euroleague on six occasions, with their most recent success coming back in 2011.