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 a PIA spokesman said the company had to deal with last-minute changes by officials to regulations and flight permissions.
Its staff were also facing intimidation, with its representative held at gunpoint for several hours, the spokesman 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.
A dire shortage of seats has meant one way tickets selling for as much as $1,200.
