Iran’s flag carrier Iran Air suspended plans to restart flights to Saudi Arabia after an eight-year hiatus, in a setback for one of the few concrete signs of the countries’ political detente.

Jeddah-bound pilgrimage flights from Tehran, Mashhad and Isfahan scheduled for Wednesday were canceled because the Saudi authorities haven’t issued the necessary permits, the state-run Islamic Republic News Agency reported, citing Iran Air Spokesman Hesam Ghorbanali.

The flights would have been the first of their kind from Iran to Saudi Arabia in eight years, IRNA said. They would also have marked a step in thawing relations between the two regional rivals, which agreed to restore diplomatic relations last March after years of hostility but are yet to finalize talks on investment.

In a televised statement, Iran’s Minister of Culture Mohammad-Mehdi Esmaeili said the problem is “a technical disagreement” between the countries’ aviation authorities, describing it as “nothing serious.”

Saudi Arabia’s General Authority of Civil Aviation didn’t immediately respond to a request for comment.