At least 12 people have been killed and 309 injured in an attack on an international airport in the Saudi capital Riyadh, local authorities say, days after Yemen's Houthis claimed to have carried out similar strikes on the hub.

The Saudi Civil Aviation Authority said the victims were four Saudi and two Bangladeshi nationals, while Egypt, Jordan, Palestine, Sudan, Syria and the US each had one of their citizens killed. Operations at King Khalid International Airport in Riyadh have been suspended.

More than a dozen ambulances were seen rushing to the airport, according to news agency Reuters, citing an eyewitness.

The US embassy said it was "aware of attacks", urging Americans to avoid the area.

Watch: The scene at Riyadh airport after the strike

A projectile also fell near King Fahd International Airport in Dammam in eastern Saudi Arabia, the Saudi-led coalition which is fighting the Houthis said.

The attack comes a day after authorities said three Saudis including a pilot were killed in two attacks on the airport by the Iran-backed Houthis the day prior. Another three people were killed in Houthi attacks on two Saudi airports on 6 and 7 October.

An eyewitness who said they had been in the domestic terminal told the news agency that they had seen gate 401 hit and "injured [people] in front of my eyes", adding: "Everyone was running."

Western embassies in Saudi Arabia have warned their citizens away from the airport, while the UK Foreign Office told British nationals to stay away "until the airport is secure and to monitor the advice of the Saudi authorities".

Several Gulf airlines said they had cancelled their flights to and from the airport, with Kuwait Airways citing the "security situation" there.

All flights to Riyadh have either been diverted or cancelled, aviation tracker Flightradar shows.

Doctors had been asked to report to hospitals to address the situation, a medical source told AFP.

"We were told we are dealing with a 'serious emergency situation'," the medical source told the agency.

The suspected attack comes during a marked escalation in renewed fighting between Yemen's Saudi-backed government forces and the Houthis, who control most of the country's north-west.

The Houthis say they are targeting Saudi Arabia over its support for government forces in Yemen's civil war.

The conflict worsened after the Houthis seized strategically important stretches of the Red Sea coast in a rapid offensive.

That included the port of Mokha on the Bab al-Mandab Strait, which is the narrowest point of the Red Sea and a chokepoint for global shipping. Yemeni pro-government forces have since said they had "secured" the strait at the southern end of the Red Sea.

A Saudi-led coalition was formed in 2015 after Arab countries joined forces to stop the Houthis taking over Yemen from the country's internationally recognised government.

A temporary ceasefire was brokered in 2022 after years of air strikes and ground fighting led to the deaths of hundreds of thousands of people, triggering one of the world's worst humanitarian crises.

The Houthis announced a "maritime embargo" against Saudi Arabia and began missile and drone attacks on Saudi airports, oil facilities and tankers in the Red Sea. They said they were retaliating against what they described as a years-long Saudi blockade and for an air strike on Sanaa airport.

Three Saudi nationals killed in Houthi attacks on Riyadh airport