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 Afghan aviation officials 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, the Gulf Air chief executive.
Under a bilateral agreement between the two countries, Gulf Air is allowed to operate eight flights a week to Afghanistan, Gulf Air said.
The carrier started flights to Kabul International Airport in June, choosing to operate four flights a 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.
On Wednesday last week, a Gulf Air 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 them on alternative flights to the Afghan capital or to 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 kingdom's regulatory authority for air transport, has now taken up the matter with the Civil Aviation Authority in Afghanistan.
The refusal to permit landing contravened International Civil Aviation Organizationagreements and protocols, said Gulf Air. No other airlines operating higher frequencies had been subjected to the same measures.
Despite only a few foreign airlines operating services to Kabul, air travel to Afghanistan is in high demand because of the military and reconstruction activity in the country.
At the same time, carriers in Afghanistan have been looking to increase their own services. East Horizon Airlines, the passenger and cargo service, aims to start operations by next month.
The budget airline flydubai launched services to Kabul in May last year.
Although passenger services to Kabul from the Gulf are limited, the region is an important onward route for cargo.
Emirates Airline last year began dedicated cargo services to Bagram Air Base, the airfield run by the US army. Midex Airlines, a dedicated cargo airline based in the UAE, said it carried freight to Afghanistan from the Emirates and Bahrain daily, representing 60 per cent of its business for the Middle East and North Africa region.