UAE's long-ailing leader Sheikh Khalifa bin Zayed has passed away

The United Arab Emirates' long-ailing ruler, Sheikh Khalifa bin Zayed Al Nayhan, passed away Friday

The government's state-run news agency announced in a brief statement.

He was 73. The UAE's Ministry of Presidential Affairs declared 40 days of mourning and a three-day termination of work in all ministries and the private sector beginning Friday, including flags to be flown at half-staff.

He had long seized having involvement in day-to-day affairs, with his brother, Abu Dhabi's Crown Prince Mohammed bin Zayed, seen as the de-facto ruler.

There was no immediate announcement about the successor.