The United Arab Emirates said Qatari fighter planes intercepted a civilian aircraft carrying 86 passengers to Bahrain on Sunday, UAE state news agency WAM reported.
Quoting its civil aviation authority, the agency said the UAE civilian craft had to take evasive manoeuvres to avoid a collision. It did not name the airliner involved.
Both countries have accused one another of a series of mid-air incidents since Abu Dhabi and other powers imposed travel, diplomatic and trade sanctions on Qatar in June.
The UAE, along with Saudi Arabia, Bahrain and Egypt, accuse Qatar of supporting regional foe Iran as well as Islamist extremists. Qatar has denied the charge and accused the four countries of trying to curtail its sovereignty.
There was no immediate comment by Qatari officials on the accusation.