UAE residents who were stuck abroad when the country's borders closed must show they are Covid-19 free before they board a flight home.
A new ruling by the country's federal authorities was made on Sunday night.
The National Crisis and Emergency Management Authority (Ncema) said it had identified labs in 106 cities and 17 countries where travellers could be tested. The list has yet to be released.
The statement made no specific mention of tourists returning to the Emirates.
The decision does not affect Dubai, which out its own measures for returning residents and tourists last week and rules for Dubai residents travelling abroad this summer, officials said. Since the start of the outbreak, Dubai has had some separate rules covering curfews and personal travel.
"Without the valid negative Covid-19 test taken within 72 hours of take-off, individuals will not be permitted to board the aircraft," Ncema said.
"Accredited laboratories are aware of the time constraints and will deliver results digitally."
If residents are returning home from a country without a recognised clinic or lab, they will be tested at the airport – but must stay in quarantine for 14 days.
All arrivals must download AlHosn app and enter their personal details, which allows the authorities to trace them and send their results if they were tested.
"All costs for quarantining and medical assistance, whether at home or in another designated facility, will be at the cost of the individual primarily," NCEMA said.
"In certain circumstances, the companies at which these returning individuals are employed shall need to bear all costs related to the medical examination and quarantine."
Dubai's authorities last week said that tourists must be tested and bring a certificate with them showing they are Covid-free.
Returning residents did not require a test before they boarded and would be swabbed on arrival.
The emirate did not impose a 14-day quarantine on arrivals, as Ncema mandated on Sunday night, but said travellers must isolate until the results were ready, which can take several days.