The court also confirmed a life term against three accomplices, a Bidoon (stateless Arab), a Bangladeshi and an Indian. Two others, a Lebanese and an Iraqi, were sentenced to seven years in jail each.
The lower criminal court in January sentenced the royal, named only as Sheikh Talal, to death — a first in the history of the oil-rich Gulf state.
The sentence must be confirmed by the supreme court and then signed by the ruler before the royal could be executed by hanging.
Kuwaiti police arrested the group in April last year with a large drugs haul, including at least 10 kilogrammes (22 pounds) of cocaine and 120 kilogrammes (260 pounds) of hashish.
The arrest was made on the orders of Kuwait’s Defence Minister Sheikh Jaber al-Mubarak al-Sabah, a former interior minister who is a leading figure in the ruling family.
