The United Nations-mediated peace talks on Yemen have stalled pending the arrival of the Shiite rebels who said they didn't attend because they were not guaranteed safe return after the discussions.

The talks, meant to be the first between Yemen's warring parties in two years, were scheduled for Thursday in Geneva. A delegation from Yemen's internationally recognized government headed by Foreign Minister Khaled al-Yamani arrived but the rebels, known as the Houthis, have not.

The Houthis insist on traveling to Geneva on an Omani flight, saying it would ensure their safe return to Yemen.

"We want guarantees on our return to Yemen," senior Houthi official Deif Allah al-Shami said Friday.

On Thursday, senior rebel official Mohammed Ali al-Houthi said on Twitter that the Saudi-led coalition backing Yemen's internationally recognized government refused to grant the Omani flight authorization to transfer their delegation to Geneva. He said the refusal raises the risk of being prevented from returning to Yemen as happened in 2016 after a failed round of talks.

The coalition, which has imposed a land, sea and air blockade on Yemen since 2016, denied the allegation.

The official SABA news agency carried a Yemeni government statement on Friday blaming the Houthis for hindering the talks and saying their failure to attend shows "their intention to thwart any steps taken by the U.N. envoy to bring peace and alleviate the suffering of the Yemeni people."

The U.N. special envoy for Yemen, Martin Griffiths, held consultations with Yemen's government delegation on "confidence-building measures including the issue of prisoners, humanitarian access, the reopening of Sanaa airport in addition to economic issues," U.N. spokeswoman Alessandra Vellucci said Friday.

"The special envoy for Yemen also met with diplomats and is still working on getting the Ansar Allah delegation (Houthis) to Geneva," she said.

Yemen has been embroiled in a war pitting the Saudi-led coalition backing the government of Abed Rabbo Mansour Hadi against the Iran-aligned rebels since March 2015. Saudi-led airstrikes have hit schools, hospitals and wedding parties and killed thousands of Yemeni civilians. The Houthis have fired long-range missiles into Saudi Arabia and targeted vessels in the Red Sea.

An estimated 10,000 people have been killed in Yemen's conflict, which has spawned what the U.N. calls the world's worst humanitarian crisis.