DUBAI (Agencies) - United Arab Emirates President Shaikh Khalifa bin Zayed Al Nahyan on Tuesday announced the death of Shaikh Nasser bin Zayed Al Nahyan, who died on Monday night when a helicopter carrying him and his colleagues crashed into the Gulf waters. Shaikh Nasser was the brother of President Shaikh Khalifa bin Zayed. The Ministry of Presidential Affairs announced three days official mourning starting Tuesday. Shaikh Mohammad bin Rashid Al Maktoum, Vice-President and Prime Minister of the UAE and Ruler of Dubai, also declared a three-day mourning period starting on Tuesday in Dubai. During the period of mourning for Shaikh Nasser bin Zayed Al Nahyan, work in all government departments and in the rest of the public and private sectors will continue as normal, and there will be no closure of offices, it has been announced by an authorised source at the Ministry of Cabinet Affairs. Funeral prayers for Shaikh Nasser and his colleagues were performed at the Shaikh Sultan bin Zayed Mosque in Al Bateen. Shaikh Khalifa and Shaikh Mohammed bin Rashid attended the funeral rites. Officials did not say what caused the crash or how many people were on the aircraft.