The UN has expressed great concern on the Houthi missile attack on the Saudi southern airport of Abha early Wednesday.
The escalation is a serious threat that would undermine the UN-led political processin Yemen, UN spokesman Farhan Haq told reporters on Wednesday, calling on all parties to avoid such events.
The United Nations is urging both parties to exert more efforts to reengage in the political process, end the conflict and work on Yemeni all-inclusive dialogue, he added at press conference.
Earlier on Wednesday, the Saudi-led coalition said Abha airport was under "terrorist act" through shell fired by Houthi group that claimed responsibility for the attack, saying it struck the airport's observation tower with cruise missile.
This is the second attack by the Iranian-backed Houthis into Saudi lands, one month after the rebels targeted two Saudi oil pumping stations outside Riyadh.
The first attack pushed Saudis to invite for two emergency summits in Mecca late last May to discuss how to confront "Iranian threats".
Houthis sporadically fire ballistic missiles and send attack droneson Saudi territory "in retaliation to coalition airstrikes that target Yemeni civilians and infrastructure," while Saudi Arabia accuses Iran of providing Houthis with such missiles.
Yemen has been racked by a 4-year bloody conflict between the internationally-recognized Yemeni government's forces, backed by a Saudi-led coalition, and the Iranian-backed Houthi rebels who ousted the government in 2014.
Saudi Arabia has been leading a military coalition in Yemen since 26 March 2015, in support of forces loyal to President Hadi to retake areas controlled by Houthi (Ansarullah) group seen as proxy for Iran in the Arab Peninsula country.