The peace talks had been scheduled to start Thursday in Geneva. Several Yemeni officials said over the weekend they had been informed that the talks were postponed, but the U.N. statement was the first official confirmation.

Secretary-General Ban Ki-moon ordered the postponement, spokesman Stephane Dujarric said, adding that Ban “is actively working to convene the talks at the earliest possible time.”

The talks were meant to end weeks of heavy fighting and Saudi-led airstrikes against an Iran-backed Shiite militia group known as the Houthis amid a humanitarian crisis that has left millions in the Arab world’s poorest country short of food and fuel.

Dujarric said Ban is disappointed that the U.N.-sponsored talks weren’t starting on schedule and again called on all parties to participate “in good faith.”

Despite the U.N. appeal for all parties to attend the talks without preconditions, the exiled government of President Abedrabbu Mansour Hadi had reiterated its demand that Houthi militia first pull out of cities and towns seized in recent months, including the capital, Sanaa.

The Houthis backed the talks and said they would participate. Houthi militia leader Abdul-Malek al-Houthi had described talks as the only solution to the war, a view backed by the U.N. chief. Al-Houthi boycotted a recent conference hosted by Saudi Arabia, demanding that peace negotiations be held in a neutral country.

The talks, announced last week, were the first major initiative of the new U.N. special envoy for Yemen, Ismail Ould Cheikh Ahmed, who this month held meetings in Yemen with rival political players.

Ban asked Ahmed to redouble his efforts with all parties and countries in the region “with the aim of producing a comprehensive ceasefire and the resumption of peaceful dialogue and an orderly political transition,” Dujarric said.

Ban noted the escalation in fighting following a five-day humanitarian pause that ended last week and urged all parties “to be mindful of the suffering of Yemeni civilians” caused by a delay in returning to peace talks, the spokesman said.