ZURICH, May 14 (Reuters) - Deportivo Alaves forward Munir El Haddadi's hopes of playing for Morocco ended on Monday when sport's highest tribunal rejected his appeal against a FIFA ruling that stopped him switching allegiance from Spain.

FIFA rules bar players from changing national teams once they have played a competitive international, even if they hold dual nationality, and the global soccer body had rejected Munir's request to play for Morocco in March.

"Such decision is now confirmed and the request to change the sporting nationality of Munir El Haddadi from Spain to Morocco remains denied," said CAS in a statement, without giving further details.

The 22-year-old made a single appearance for Spain, in a European championship qualifier against Macedonia in September 2014, when he came on as a substitute and played less than 15 minutes.

Munir, who made his appeal jointly with the Moroccan Football Federation, had asked for a fast-track ruling in the hope of playing for the North Africans at next month's World Cup in Russia.

Munir, who was born in Spain and has a Moroccan father, was raised at Barcelona’s famous youth academy where he made his professional debut and is currently on loan at Alaves. He has also spent one season on loan at Valencia.

FIFA’s stakeholders committee is studying a proposal to make the rules more flexible in such cases. (Writing by Brian Homewood in Bern, editing by Pritha Sarkar)