US embassies issue security alerts over Houthi attacks on Saudi Arabia

US embassies across the Middle East have issued security alerts warning Americans to maintain "heightened vigilance" following attacks by Yemen's Iran-aligned Houthi rebels on Saudi Arabia.

Embassies in Bahrain, Israel, Iraq, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, and the UAE said the "military conflict has the potential to escalate rapidly" and that the security environment remained "complex."

The alerts also advised people to "be aware of potential flight cancellations, airspace closures, and travel disruptions."

It comes after the Houthi rebels on Saturday said they had carried out two operations using ballistic and cruise missiles as well as drones to target Saudi Arabia in response to Saudi attacks.

"The first targeted sensitive sites in the Saudi capital, Riyadh, and the second targeted Aramco facilities in Yanbu," the group claimed.

A spokesperson for the Saudi-led coalition forces - which were formed in 2015 to back Yemen's internationally recognised government - later confirmed that the Royal Saudi Air Defense Forces had intercepted a ballistic missile fired towards Riyadh. The spokesperson added that the group had also targeted the cities of Baish, Taif, Farasan, and Yanbu.

On Saturday, residents of Riyadh reported seeing flames and smoke at the capital's King Khalid International Airport.

Video footage circulating on social media appeared to show a towering column of smoke rising from the airport, which flight tracking site Flightradar24 had said was experiencing "major problems."

Yemen's Houthi rebels, who declared a naval blockade of Saudi Arabia in July, have been launching increasing attacks on Saudi cities and shipping, further heightening tensions in the Middle East.

Saudi Arabia has hit back with its own strikes on the group - which has seized vast stretches of territory in Yemen this month in a lightning offensive - but has failed to stop its advance.

In a press briefing on Friday, Stéphane Dujarric, a spokesperson for the UN Secretary-General, addressed the situation in Yemen.

"Since hostilities escalated in August, the Human Rights office has documented 110 civilian casualties in 31 incidents, including 28 killed and 82 injured, across Taizz, Al Hudaydah and Marib. Insecurity and access constraints continue to hamper our ability to verify the actual number as you can imagine is very likely higher," Dujarric said, according to a transcript shared by the UN.

"We urge all parties, and those with influence over them, to act immediately to de-escalate, protect civilians and facilitate humanitarian access. Every effort must be made to prevent further loss of life," he added.