The Saudi-led military coalition vowed to respond firmly to a missile attack by Yemeni Houthi forces on a civilian airport in southern Saudi Arabia on Wednesday which wounded 26 people.

The Western-backed alliance that has been battling the Iran-aligned Houthi movement in Yemen said the early morning attack proved Tehran's support for what it called cross-border terrorism.

A coalition statement said a projectile hit the arrivals hall at Abha airport, causing material damage. Three women and two children were among the wounded, who were of Saudi, Yemeni and Indian nationalities, it said.

The Houthis said on their media channels that they had fired a cruise missile at Abha airport, which is about 200 km (125 miles) north of the Yemen border and serves domestic and regional routes.

Saudi Arabia's civil aviation body told Reuters air traffic was currently running normally at the airport. The Houthi media centre said the strike destroyed the control tower. The coalition's spokesman did not immediately respond to a request for comment. Reuters could not independently verify the claim.

The attack follows an armed drone strike last month on two oil-pumping stations in the kingdom that were claimed by the Houthis. Saudi Arabia accused Iran of ordering the attack, a charge that Tehran and the Houthi movement deny.

The coalition said the attack could amount to a war crime. It would take “urgent and timely” measures in response, it said.

“This attack also proves this terrorist militia's acquisition of new special weapons; the continuation of the Iranian regime's support and practice of cross-border terrorism...,” the coalition's English-language statement said. There was no immediate Iranian response.

A Houthi military spokesman on Tuesday threatened that the group would target every airport in Saudi Arabia and that the coming days would reveal “big surprises”.

The alliance led by Saudi Arabia and the United Arab Emirates intervened in Yemen in 2015 to try to restore the internationally recognised government that was ousted from power in the capital Sanaa by the Houthis in late 2014.

The conflict is widely seen in the region as a proxy war between Saudi Arabia and Iran. The Houthis deny being puppets of Iran and say their revolution is against corruption.

A Houthi military spokesman said the attack was a response to the coalition's “crimes” against Yemen. “The most modern American systems could not intercept the missile,” he said in comments carried by the group's media centre.

The coalition spokesman did not immediately respond when asked if the projectile had been intercepted by the kingdom's Patriot missiles before hitting the airport.

The Houthis have previously targeted Saudi cities with drones and missiles, most of which have been intercepted. In March 2018 an Egyptian was killed in Riyadh by missile shrapnel.

The nearest Patriot battery to Abha airport is about 20km to the north, said Jeremy Binnie, Middle East & Africa editor of Jane's Defence Weekly.

“A cruise missile might be able to come in at a sufficiently low altitude that it could not be engaged before reaching its target,” he said.

The Houthi group last month stepped up its attacks following a lull last year ahead of UN-led peace efforts. The coalition has responded by carrying out air strikes on Houthi-held Sanaa.

Bahrain, a close ally of Riyadh and home to the US Navy's Fifth Fleet, said Wednesday's attack was a serious escalation carried out by Iranian weapons, and called for a “a clear and firm international stance”.

The strike took place against a backdrop of heightened US-Iranian tension following Washington's move to tighten sanctions on Tehran and to reinforce its military presence in the Gulf.

The escalation in violence could threaten a fragile UN-led peace initiative in Yemen's main port city of Hodeidah, which handles the bulk of the impoverished country's commercial and aid imports and is a lifeline for millions of Yemenis.

Pakistan condemns attack

Pakistan strongly condemned the missile attack by Houthi militants at the Abha airport that resulted in 26 casualties.

"Pakistan reiterates its full support and solidarity with the brotherly Kingdom of Saudi Arabia against any threats to its security and territorial integrity," said a statement released by the Foreign Office.