Visa issues for players and officials ahead of the FIFA World Cup in the US have raised immigration concerns.

Team staffers, federation leaders, media members, and at least one referee and player have dealt with travel issues ahead of the World Cup.

The referee was "determined to be inadmissible due to vetting concerns and was denied entry," a CBP spokesperson said, without going into further detail.

CBP cites ‘vetting concerns’ after Somali referee Omar Artan arrived in Miami.