A Somali referee on course to become the first official from the Horn of Africa nation to work at a FIFA World Cup finals tournament has been refused entry to the United States, casting uncertainty over a landmark moment for Somali football.

It was not immediately clear why Artan was barred from entering the U.S. at Miami International Airport, but Somalia is one of several countries on a travel ban list introduced by President Donald Trump's administration.

"Omar Artan is among Africa's most respected referees and deserves the support of the entire football community," Ciise Aden Abshir, a senior advisor to Somalia's Ministry of Youth and Sports and a former national team captain, told AFP.

Artan had a valid visa for the U.S., Abshir said. He has flown back to Istanbul, where he has been staying.

"Denying him entry to the United States and preventing him from officiating scheduled matches harms not only him personally but also undermines football's commitment to fairness, merit, and the spirit of fair play," Abshir added.