Ahmed al Junaibi is the only Emirati rider to qualify for the competition. His horse Picobello Wodiena and Junaibi's Moroccan groom both obtained visas in time.
The 37-year-old rider has been riding with the UAE team since 1991 and has spent time in Europe without any immigration problems.
The deadline for visa approval was two days ago. He has not been told the reasons for the delay.