The first commercial flight from Yemen’s rebel-held capital in six years had to be indefinitely postponed after failing to obtain permits from the Saudi-led coalition, the national carrier said Sunday.

The capital's airport was due to receive the commercial aircraft Sunday morning, reviving hopes that the war-torn country could resume some normal operations.

A brutal seven-year conflict pitting Yemen's Saudi-backed government against Iran-backed Huthi rebels has killed hundreds of thousands and left millions on the brink of famine.

The plane operated by national carrier Yemenia was due to take passengers in need of medical treatment from Sanaa to Jordan's capital Amman as part of a two-month truce that went into effect in early April.

But hours before the flight, the airline said on its Facebook page that "it has not yet received operating permits," and expressed "deep regret to the travellers for not being allowed to operate" the long-awaited flight.

It added that it hopes "all problems will be overcome in the near future", without specifying a date for the route to operate.

One of the passengers told AFP that he had received a call from the airline asking him not to go to the airport.

A manager at the company told AFP that "the needed permission from the coalition didn’t arrive."

There was no immediate reaction from the military coalition that controls Yemen's airspace.

The Huthis took over Sanaa in 2014, prompting a Saudi-led military intervention to support the government the following year and igniting a war that has caused what the United Nations terms the world's worst humanitarian crisis.

The airport in Huthi-controlled Sanaa has been closed to commercial traffic since August 2016 when airstrikes disrupted service to the city.

Aid flights continue to land in Sanaa, although service has periodically halted.

The pause of commercial flights has prevented "thousands of sick Yemeni civilians from seeking urgent medical treatment outside the country," humanitarian groups CARE and the Norwegian Refugee Council said last August.

They also cited "economic losses estimated to be in the billions."

Daily flights out of government-controlled Aden (south) and Seiyun (center) operate domestically and connect Yemen to other countries in the region.