United Arab Emirates President Sheikh Khalifa Bin Zayed Al Nahyan has died, aged 73, the nation’s official news agency WAM reported on Friday.

The emirate’s Ministry of Presidential Affairs has announced that there will be 40 days of official mourning, including flags at half-mast and the closure of ministries and official entities at the federal and local levels and in the private sector.

Sheikh Zayed was also the Emir of oil-rich Abu Dhabi and the supreme commander of UAE’s Armed Forces since 2004.

In a statement published by WAM, the Ministry of Presidential Affairs expressed its condolences to the people of the UAE and the Arab and Islamic nations and the world on the death of the leader of the nation and the guardian of its journey, local media reports said.

No cause of death has been revealed yet by UAE's official news agency.

Crown Prince Mohammed Bin Zayed Al Nahyan, who has been managing day-to-day affairs in the emirate on behalf of Sheikh Zyed for many years, is likely to be elevated to the emirate’s top position.