The United Arab Emirates has claimed Qatari fighter jets intercepted two of its commercial airliners in international airspace on the way to Bahrain.
The allegations have been denied by Qatar, and the UAE's two major airlines have declined to comment.
The claim could further escalate tensions between Qatar and the four Arab nations which have been boycotting it for months, among them the UAE, home to the world's busiest international airport.
It follows two complaints by Qatar to the United Nations about Emirati military aircraft allegedly violating its international airspace amid the diplomatic crisis.
The UAE's state-run WAM news agency made the claim today, citing the country's General Civil Aviation Authority.
"The GCAA received a message from one of the UAE's national carriers on Monday morning that one of its aircraft on a flight to Manama on a normal route had been intercepted by Qatari fighters," the report said.
"The flight was a regular, scheduled service on a known flight-path that met all the required and internationally recognised approvals and permits."
WAM said a second flight to Bahrain was similarly "intercepted".
It did not identify the aircraft involved, nor did it elaborate on details of the purported encounters.
Saif Al Thani, a Qatari government spokesman, denied the UAE's claim on Twitter, calling it "completely untrue".
The UAE is home to two major national carriers, Abu Dhabi-based Etihad and Dubai-based Emirates.
Both airlines declined to comment, though Bahrain's foreign ministry identified one of the affected aircraft as Emirates flight No EK837.
That flight left Dubai at at 8.20am local time (4.20am Irish Time) today and landed 46 minutes later, flying out over international waters near the northern tip of Qatar, a peninsular nation that juts out like a thumb into the Persian Gulf, before arriving in the island nation of Bahrain. This has been the standard route of all Emirati commercial airliners since the crisis began.
FlightRadar24, a popular plane tracking website, did not show any unusual routes between the UAE and Bahrain.
"There appears to be no deviation from standard routing and approach patterns in today's flights," FlightRadar24 spokesman Ian Petchenik said.