Yemen’s Houthis have launched a missile attack on Riyadh’s international airport in Saudi Arabia, killing at least 12 people and leaving hundreds wounded, the Saudi Civil Aviation Authority has said.

Operations at King Khalid international airport in Riyadh were suspended as ambulances rushed to the airport. More than 300 people were reported injured in the deadliest attack in any Gulf Arab country since the start of the Iran war.

A projectile also fell near the King Fahd international airport in Dammam, according to the Saudi-led coalition fighting the Houthis. The Dammam airport has become an important alternative to Riyadh amid the recent spate of attacks.

Donald Trump said he was evaluating whether the US should join Saudi strikes against the Iran-backed Houthi rebels in neighbouring Yemen.

“We may. We’re going to look at it,” Trump said. “We just found out about the recent attack. So we’ll make a decision. We move very quickly.”

A Saudi government statement said the dead included four Saudi citizens, as well as two Bangladeshi nationals, a Palestinian, a US citizen, an Egyptian, a Jordanian, a Syrian and a Sudanese.

One witness at the Riyadh airport reported hearing an explosion while waiting to board a flight, and another said they saw a strike that left people wounded.

“I was on gate 403,” at the domestic terminal, the witness told the Agence France-Presse news agency. “I saw [gate] 401 hit, I saw injured [people] in front of my eyes. Everyone was running.”

The relative of one injured person said they had been wounded in the shoulders and arms by shattered glass and taken to hospital.

A missile struck an airport complex housing terminals 3 and 4 for domestic flights, a regional official said, speaking on condition of anonymity because they weren’t authorised to speak to the media.

Saturday’s incident comes amid an escalation of missile strikes by Yemen’s Iran-aligned Houthis ⁠on the kingdom. The airport has already been attacked twice this ​week, leaving four people dead and ‌others wounded, and ‌badly damaging an aircraft.

The Houthis have repeatedly attacked Saudi airports, oil facilities and tankers after a truce in their long-running war with Yemen’s Riyadh-backed government unravelled in July.

The attack came as forces allied to the UN-recognised government in Yemen claim to have mounted a successful offensive to retake the Bab al-Mandab strait from Houthi rebels, but accounts vary as to whether the push has been repelled.

A Houthi spokesperson said forces from the Saudi-backed government based in Aden “were targeted with a large number of ballistic missiles, artillery support and heavy weapons, resulting in the destruction of more than 22 armoured vehicles and the killing and wounding of dozens, including a number of commanders.

“More than 30 ambulances arrived in Aden to transport the dead and wounded from the Saudi enemy’s mobilisations.”

By contrast, the Saudi ambassador to Yemen, Mohammed al-Jaber, said: “Blessed Friday and victory for every Yemeni and Arab. Bab al-Mandab has been cleared of the remnants of the Houthi terrorist militia.”

The exposed 5 sq mile (13 sq km) Perim Island straddles the strait, acting as a lookout point for all traffic from the Red Sea into the Gulf of Aden and towards the Indian Ocean. Aidarous al-Zubaidi, the president of the Southern Transitional Council (STC), one of the main political forces in the south of Yemen, claimed the island and coastal area had been recaptured from Houthi hands.

An official military spokesperson for the UN-recognised government forces qualified the claim, saying only half the area had been recaptured so far. Waddah al-Dabish said newly established Houthi defensive lines had been broken on the land next to the strait, leading to the death of thousands of Houthi fighters.

It is thought that as many as 500 Houthi fighters are stationed on the island, and Saudi Arabia is desperate to be able to report that the strait has been reclaimed to show that the land counteroffensive it launched at the beginning of the week is advancing.

The report came as the United Nations’ special envoy to Yemen, Hans Grundberg, admitted to the UN security council in New York that Yemen – one of the poorest countries in the world – had lapsed back into full-scale war and said the first victims would be women and children.

The Houthis seized control of the strait two weeks ago and said no Saudi-linked commercial traffic would be permitted to go through the narrow waterway. The Houthis are waging a war to remove Saudi influence from Yemen, and have been mounting missile attacks on Riyadh in support of this objective.

There have been previous premature reports of military breakthroughs by the Saudi-backed Yemeni government since it launched its counteroffensive at the start of the week, but the recapture of the land by the strait and Perim Island (also known as Mayyun Island) is a military prize western governments desperately need.