Flames and a large plume of black smoke were seen rising above Riyadh airport in Saudi Arabia on Saturday after the government sent air-raid alerts to citizens by phone overnight warning of aerial attacks.

Explosions were heard in the capital and firefighters battled to extinguish the flames of a burning fuel tank emblazoned with the logo of the Saudi oil company Aramco near the city’s King Khalid international airport.

It is the first time the government has issued such alerts for Riyadh since fighting with the Iran-backed Houthis in neighbouring Yemen escalated in July.

Residents told Agence France-Presse that hours after the alert, they had heard what sounded like another round of explosions echoing through parts of the Saudi capital.

According to tracking website FlightRadar24, there are “major problems” at the airport and it has been listed under its maximum disruption index.

“In the direction of the airport, we saw black smoke and fire,” one resident told AFP, speaking on condition of anonymity.

The Saudi civil defence force sent air-raid alerts overnight on Friday to residents of Riyadh, Jeddah and other cities including Yanbu, a major industrial port which is home to critical oil facilities.

The all-clear was given shortly afterwards, but residents were encouraged not to gather in crowds.

The UN security council condemned the continued ​Houthi attacks against Saudi Arabia in a statement on Friday. It said they had included attacks that affected civilian and energy infrastructure and had injured civilians, including women and children.

It also condemned the Houthis’ military offensive in Yemen, where nearly 105,000 people have fled their homes, the International Organization for Migration said on Wednesday.

The security council’s 15 members called for “practical cooperation” to prevent the Houthis from acquiring arms, military training, financing and other military-related assistance needed to carry out their attacks. They stressed that all countries must enforce the UN arms embargo against the group.

The Houthi military spokesperson Yahya Saree said the group had foiled unspecified “criminal attempts” ⁠in the Yemeni capital of Sana’a, blaming Saudi Arabia and vowing a response. The group also says the Saudi air force has conducted hundreds of airstrikes against it in recent days.

The Houthis recently seized control of strategic the Red Sea islands of Greater and Lesser Hanish. Earlier this month, the group captured the port of Mokha and Perim island in the Bab al-Mandab strait, fueling fears the world could face a second oil supply crisis.