Yemen's Houthis vowed on Wednesday to press on with attacks on airports and oil facilities in Saudi Arabia and said they struck the headquarters of oil giant Saudi Aramco, which was hit the day before.
The Iran-aligned group said it had launched ballistic missiles, cruise missiles and drones at Saudi Aramco facilities in the eastern city of Dhahran, King Khalid International Airport in Riyadh and an Aramco refinery in Riyadh, without saying when.
Saudi Arabia has faced widening Houthi strikes over the past week, including an attack on Riyadh airport on Saturday that killed 13 people.
The Houthis say they have been retaliating for the kingdom's backing of Yemeni government forces in the Yemen war that restarted last month, reignited by the US-Iran confrontation in the Gulf.
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Saudi-led forces say they intercept missile
In a broad threat, the Houthis urged "international shipping companies", civilians and workers to evacuate airports and oil facilities, which they declared legitimate military targets.
The Saudi-led coalition said it had intercepted a ballistic missile fired by the Houthis towards Riyadh on Wednesday, and several loud booms were heard in the Saudi capital.
Saudi authorities earlier issued an alert for a possible aerial threat in Riyadh on Wednesday before the warning was lifted, a witness said. It wasn't immediately clear what caused the booms and there was no immediate comment from the authorities on their source.
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The escalating conflict has dealt a blow to Saudi Crown Prince Mohammed bin Salman's ambitious plans to transform and diversify the Saudi economy and reduce its reliance on oil.
The Saudi Energy Ministry said Tuesday's attack on the headquarters of Saudi Aramco had caused a limited fire and no injuries or deaths.
The Dhahran complex hosts a major operations centre for Aramco, which oversees a vast network of onshore and offshore oil rigs, pipelines, refineries and export terminals.
A company source told Reuters earlier that a ballistic missile hit the Aramco headquarters complex. The source said an office tower in the complex was struck and that its top three floors were damaged.
Riyadh's international airport has come under attack four times, including Saturday's attack which was the deadliest in Saudi Arabia in a decade. Authorities have closed the airport until October 17, and airlines have canceled flights to Saudi Arabia.
Fearing the rise of Iranian influence and the prospect of chaos on its borders, Saudi Arabia intervened in Yemen's civil war in support of the government in 2015 after the Houthis seized the capital Sanaa.
The UN brokered a 2022 truce between the warring sides in Yemen that kept a fragile peace until this year.