Pakistan International Airlines has suspended flights to the Afghan capital Kabul, citing "heavy-handed" interference from the Taliban.
The decision came after the Taliban ordered the airline to cut prices to levels seen before the fall of the Western-backed government in August.
PIA has been the only foreign carrier operating regular flights out of Kabul.
Tickets to the Pakistani capital, Islamabad, had been selling for up to 10 times the August rate.
The Taliban government's Transport Ministry said in a statement quoted by Reuters that tickets should "be adjusted to correspond with the conditions of a ticket before the victory of the Islamic Emirate", i.e. $120-150 (£87-110).
It urged passengers to report any violations of this order, which was also directed at Afghan carrier Kam Air.
Flights could be banned if the airlines did not comply, it added.
But PIA spokesman Abdullah Khan said the company had to deal with last-minute changes by officials to regulations and flight permissions.
Its staffers were also facing intimidation, with its representative held at gunpoint for several hours, Khan added.
Services between the two countries have been severely limited since international flights resumed last month following the departure of US troops at the end of August.
Khan said that insurance premiums were so high that it was impossible to operate scheduled flights and that the airline's decision to resume charter flights on 13 September had been taken on humanitarian grounds.
A dire shortage of seats has meant one-way tickets selling for as much as $1,200.
However, there has been a disappointment at PIA's decision from some passengers.
"We are in bad need of these flights. The borders are closed, now if the airport is closed, it is like we are all in a cage," pharmaceutical company employee Abdullah told Reuters.
