Rescuers from at least five countries have reportedly joined the search for missing Sheikh Ahmed bin Zayed Al Nahyan, the brother of the UAE President whose glider crashed in Morocco on Friday.
UAE daily The National has reported that Moroccan, Spanish and UAE rescuers have now been joined by specialist teams from France and America.
Sheikh Ahmed bin Zayed Al Nahyan is managing director of the Abu Dhabi Investment Authority, considered the world's largest sovereign wealth fund with assets estimated at more than $600 billion.
The pilot, a Spanish national, survived Friday's crash into an artificial lake in an area where the Sidi Mohamed Ben Abdellah dam is located.
He remained hospitalised in a stable condition Sunday, a statement published by UAE news agency WAM said.
A Moroccan source close to the probe said the search for Sheikh Ahmed and debris from the glider, also not yet found, was complicated by recent heavy rain that had left water levels high and swamped surrounding areas.
"The dam is 100 per cent full because of strong rain that recently hit," the source said.
The UAE statement yesterday said an Emirati search team was on the scene and was being assisted by rescuers from other countries.
It also warned of "enormous difficulties in its search in a rugged area comprising mountains and vast swamp land".
The cause of the crash remains unclear.
Sheikh Ahmed is a younger brother of President His Highness Sheikh Khalifa bin Zayed Al Nahyan, who is also the ruler of Abu Dhabi, although he is not in the immediate line of succession for the throne.
He has a home in the area where the glider crashed, frequented by members of the family.