Yemen's warring parties are expected to observe a ceasefire and start U.N.-sponsored peace talks in Switzerland from Dec. 15 in a bid to end months of fighting that have killed nearly 6,000 people, the United Nations said on Monday.

Ismail Ould Cheikh Ahmed, U.N. special envoy to Yemen, said that the exiled Yemen government of President Abd-Rabbu Mansour Hadi and Iran-backed Houthis were committed to the peace process laid down by the Security Council last April.

Resolution 2216 called on all sides to end the violence and avoid unilateral actions that jeopardize a political transition. It demanded that the Houthis withdraw from all areas seized since the conflict began in September last year.

"I have been strongly encouraging the parties to work on confidence-building measures including implementing a ceasefire, the releasing of prisoners and facilitating the delivery of humanitarian supplies," Ould Cheikh Ahmed told reporters in Geneva where he announced the talks.

"We are hoping to have a ceasefire starting immediately with the talks, but in order to consolidate that and to make it a lasting and long-term and final ceasefire we need to discuss that," he added.

Forces loyal to Hadi, backed by air strikes and ground forces from a mainly Gulf Arab coalition, have been locked for nine months in a civil war with the Houthis, who rule the capital Sanaa and other cities.

Previous U.N.-mediated negotiations to end the conflict through dialogue failed as battles rage across the country and Saudi-led warplanes bomb positions of the Houthi group and its Yemeni army allies.

Ould Cheikh Ahmed said Hadi has given him a commitment that he is ready now to call for this ceasefire starting the 15th of December.

"But definitely the (Saudi-led) coalition is on board and the coalition will ensure all necessary support to make sure that the ceasefire will be holding," he added.

HOUTHIS APPROVED TALKS AGENDA

Earlier, an official from Hadi's government said that the U.N. envoy had met Hadi in Aden and Houthi officials in the Omani capital Muscat with a proposed agenda for the talks.

"The Houthis have approved the agenda blueprint," an official in Hadi's office told Reuters. "Within days a humanitarian ceasefire will be declared and steps to free prisoners and lifting the siege on the cities would begin."

The Houthi spokesman, in a posting on his Facebook page, confirmed that his group had discussed "the venue and the date for the talks planned for the middle of this month".

"Ways for a ceasefire and subsequent confidence-building steps were also discussed, and we expressed our openness to conduct a responsible and serious dialogue," the spokesman, Mohammed Abdul-Salam, added.

Ould Cheikh Ahmed also condemned the car bomb killing of Aden's governor on Sunday, an attack for which Islamist State claimed responsibility, as a "painful illustration of the dangers Yemen is facing if we don't go quickly to the negotiation table".

"We will be ensuring that there is no vacuum of security, particularly when we know the risk we are facing today in terms of the development of terrorist groups," he said.

The talks, at a Swiss venue to be announced, would be "Yemeni-Yemeni", the U.N. mediator said.