A row over landing slots between Bahrain's Gulf Air and Afghanistan has escalated to government level after two of the airline's flights were refused entry to Kabul.
Gulf Air is accusing the country's aviation authorities of breaching international rules controlling landing rights.
"The Afghan authorities recently advised the airline to reduce its flights from four to two without justifiable reason and in direct contravention of the bilateral agreement in place between the Kingdom of Bahrain and Afghanistan," said Samer Majali, Gulf Air chief executive.
Under a bilateral agreement between Bahrain and Afghanistan, Gulf Air is allowed to operate eight flights per week to Afghanistan, Gulf Air says.
It started flights to Kabul International Airport in June, choosing to operate only four flights per week. With the launch, Gulf Air became the first full-service commercial carrier in the Middle East to connect to Afghanistan.
But problems emerged barely three months into the service.
Last Wednesday, a Gulf Airbus A320 was refused permission to land in Kabul by the Civil Aviation Authority in Afghanistan. The flight carrying 117 passengers was forced to return to Bahrain, where the airline had to scramble to accommodate the passengers on alternative flights to Kabul or their destination of origin.
Since then another plane bound for Kabul remained grounded in Bahrain because it was also refused entry.
Bahrain Civil Aviation Affairs, the regulatory authority for air transport in Bahrain, has now taken up the matter with the Civil Aviation Authority in Afghanistan.