Yemen's Houthi rebel negotiators board a plane to depart for attending the upcoming peace talks in Sweden, in Sanaa, Yemen, on Dec. 4, 2018. (Xinhua/Mohammed Mohammed)

SANAA, Dec. 4 (Xinhua) -- Yemen's Houthi rebel negotiators accompanied by visiting UN envoy Martin Griffiths left rebel-held capital Sanaa for Stockholm on a Kuwaiti plane on Tuesday afternoon to attend upcoming peace talks, a Xinhua reporter at the airport witnessed.

Griffiths arrived in Sanaa a day earlier in a brief stop, during which he met rebel leaders, including Mohammed Ali Al-Houthi, head of Houthi Higher Revolutionary Committee, according to a statement by al-Houthi office released on Tuesday morning.

The apparent breakthrough came a day after the Saudi-led coalition allowed the evacuation of 50 wounded rebels from Sanaa to Oman on a UN-chartered plane for medical treatment.

The Tuesday's flight consisted of a number of the Houthi delegates from Sanaa, while the head of the Houthi rebel negotiator Mohammed Abdulsalam and the rest of the delegation have been already in Oman and were set to head for Stockholm on Wednesday, a Houthi media official at the Houthi-controlled Information Ministry in Sanaa told Xinhua on Tuesday on condition of anonymity.

Meanwhile, Mohammed al-Ameri, the advisor to the internationally-recognized President Abd-Rabbu Mansour Hadi, told another Xinhua reporter on Monday that "the government delegation in the Saudi capital Riyadh was set to head for Stockholm on Thursday."

On Monday night, the Houthi-controlled Information Ministry said in a statement that the UN envoy's office informed the Houthi side that the coalition-backed Yemeni government "signed a UN-brokered agreement for exchanging war prisoners and we (Houthis) signed it too."

Also, the Houthi negotiating delegation received guarantees from the UN for a safe depart and return to Sanaa, a Houthi official said on anonymity.

The evacuation of injured, also receiving guarantee for safe return and the signing of the prisoner exchange deal, were part of "the confidence-building framework" between the Yemeni rival parties, and particularly fulfilled demands the Houthis had made before they attend the peace talks.

Griffiths' office in Jordanian capital Amman has told Xinhua that the talks in Stockholm would likely start in next few days.

The upcoming round of talks would be the second attempt by the UN envoy to bring the rival Yemeni parties on the negotiating table, just nearly three months after a previous round in September in Geneva collapsed as the Houthi delegation did not show up.

Saudi Arabia is leading the Arab military coalition that intervened in Yemen in March 2015 to reinstate government of President Hadi after the Houthi rebels forced him into exile.

Nearly four years of the Yemeni devastating war have killed more than 10,000 people, mostly civilians, displaced 3 million others, and pushed the country to the brink of famine.