Sheikh Ahmed bin Sultan Al Qasimi, Deputy Ruler of Sharjah, has died.
His death on Thursday will be marked by three days of mourning and flags will be flown at half-staff.
Sheikh Ahmed died in London and the mourning period will begin when his body is returned to the Emirates and funeral prayers are performed.
The Court of Sheikh Dr Sultan bin Muhammad Al Qasimi, Ruler of Sharjah, said condolences would be received through phone calls because the coronavirus outbreak is preventing gatherings.
The court said phone numbers would be made public in due course.
Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, led tributes online and offered his condolences to the Sharjah Ruler.
"Our condolences to His Highness Sheikh Dr Sultan bin Muhammad Al Qasimi and the people of the UAE on the death of Sheikh Ahmed bin Sultan Al Qasimi. May God rest his soul," he said on Twitter.
Sheikh Mohammed prayed for the family to be granted patience and solace.
"We belong to Allah and to Him we shall return," he said.
Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the Armed Forces, also paid his respects.
"My sincere condolences to my brother Sheikh Sultan bin Muhammad Al Qasimi and his family on the passing of Sheikh Ahmed bin Sultan Al Qasimi," Sheikh Mohamed said.
"I pray they are granted patience and solace during these difficult and trying times. May he rest in peace."
The Ministry of Presidential Affairs issued a statement mourning the death of the Sharjah royal.
It offered its condolences, prayers and words of comfort to Sheikh Ahmed's family.
Similar messages were issued by the offices of the Ruler of Ajman, Sheikh Humaid bin Rashid Al Nuaimi, and the Ruler of Fujairah, Sheikh Hamad bin Mohammed Al Sharqi.
They mourned the death of Sheikh Ahmed and wished the family the strength to bear their loss.
During mourning period, flags are flown at half-staff and regular radio programmes are replaced with classical music or Quran recitations.