United Nations-brokered talks designed to return peace to war-torn Yemen have been postponed, a U.N. official told AFP on Sunday, just four days before they were due to begin in Geneva.

“I can confirm that the meeting has been postponed,” the official said, without providing further explanation, amid uncertainty over who would attend.

On Saturday, Yemeni President Abedrabbo Mansour Hadi laid out his exiled government’s demands to attend the conference, including the withdrawal of Shiite rebels from territory they have seized.

Hadi fled to the Saudi capital Riyadh along with his government in late March when the Shiite Houthi militiamen advanced on his southern stronghold of Aden.

Hadi had said he was in favor of Thursday’s now-postponed talks but insisted the United Nations press the Houthis to pull back from regions they captured across Yemen, according to the official Saba news agency.

U.N. chief Ban Ki-moon had said the meeting from May 28 aimed to “restore momentum toward a Yemeni-led political transition process,” after weeks of conflict that have left nearly 2,000 people dead in Yemen.

The peace talks were suspended when Shiite Houthi rebels went on the offensive, capturing the capital Sanaa in September and advancing on Aden in the south, forcing the president to flee to Saudi Arabia.