The United States has denied entry to Omar Abdulkadir Artan, Africa’s reigning referee of the year and the first Somali selected to officiate at a FIFA World Cup, forcing him out of the tournament days before kickoff and raising fresh questions about whether U.S. immigration policies could complicate participation in football’s biggest event.

The decision has drawn criticism from Somali officials and added to growing concerns over travel restrictions affecting some World Cup participants, including members of Iran’s delegation and other visitors from countries subject to heightened U.S. scrutiny.

Artan, one of 52 referees selected by FIFA for the expanded 48-team World Cup, was turned away after arriving at Miami International Airport from Istanbul on Saturday. U.S. authorities said he was deemed inadmissible following additional screening, citing unspecified “vetting concerns”.

The Somali official had been set to make history as the first person from his country to referee a World Cup match.

A spokesperson for the U.S. Department of Homeland Security confirmed that Artan was denied entry after an inspection by Customs and Border Protection officers.