A large plume of smoke was visible near Riyadh's main airport on Saturday after booms were heard and Saudi Arabia sent alerts overnight warning of potential danger around the capital, amid an escalation in attacks by Yemen's Houthi ​group.

Reuters video and photographs showed a huge pillar of black smoke rising in the area, with ​the airport highway, main terminal building and other facilities in the foreground. At one ⁠point in the video, flames were visible rising from behind what appeared to be fuel tanks.

There was no ​immediate comment from the Saudi government's media office in response to Reuters questions about the smoke and the ​overnight alerts.

Saudi civil defence sent the alerts by phone overnight for potential danger of aerial attacks in Riyadh and the city of Al-Kharj east of the capital, before issuing an all-clear on Saturday morning. A Reuters journalist in Riyadh's Olaya area heard ​booms before the all-clear was sent.

Although some alerts had been issued in Riyadh this year after the ​start of the US-Iran war, these were the first since the escalation began with the Houthis in July.

HOUTHI WARNING

The Houthis, who control ‌the ⁠most populous parts of Yemen and much of the north, have been launching attacks against Saudi Arabia since declaring a naval blockade against Riyadh in July, with strikes targeting Saudi vessels in the Red Sea.

The attacks have targeted Saudi cities, energy infrastructure and shipping, creating new threats to global oil supplies and putting at risk the main alternative Red ​Sea route for Gulf ​exports while traffic through ⁠the Strait of Hormuz remains blockaded.

On Friday Houthi military spokesperson Yahya Saree said the group had foiled unspecified "criminal attempts" in the Yemeni capital Sanaa, blaming Saudi Arabia and ​vowing a response.

The Iran-aligned group, which seized Yemen's entire Red Sea coast in ​a lightning advance ⁠this month, says the Saudi Air Force has conducted hundreds of airstrikes against it in recent days.