“Due to tensions in the Middle East, the security environment remains complex with the potential for unforeseen escalation. Americans currently in the Middle East should exercise heightened vigilance and be aware of potential flight cancellations, airspace closures, and travel disruptions,” the US Department of State said in a Facebook post.

The department said Iranian-backed Houthi rebels have engaged in hostilities against Saudi Arabia, including attacks affecting civilian airports, warning that the conflict could escalate rapidly.

The State Department also advised Americans outside the Middle East to seriously reconsider travel to and through the region.

“Those who do travel to or from the region should monitor information about airport and airline operations. U.S. diplomatic facilities, including outside the Middle East, have been targeted,” the department said.

It further warned that Iran and groups supportive of Iran could target other US interests overseas or locations associated with the United States and Americans around the world, including US businesses and other institutions.

Meanwhile, Yemen's Houthi rebels launched a fresh wave of missile and drone attacks targeting Saudi Arabia on Saturday. The Saudi-led coalition said it intercepted and destroyed a ballistic missile fired towards the capital, Riyadh.

The attack marked the first reported targeting of Riyadh since the latest escalation in fighting between the Houthis and Saudi-backed forces began in July.

The missile attack came hours after a fire broke out at a fuel depot near King Khalid International Airport in Riyadh.

Firefighters were seen battling flames from a fuel tank bearing the logo of Saudi oil giant Aramco. Footage verified by AFP showed a large column of black smoke rising above the airport area.

The developments come amid heightened regional tensions, with authorities warning of possible further disruptions to air travel and security across the Middle East.