Saudi Arabia issues emergency alerts over ‘potential danger’ in Jeddah, Makkah, Taif

The Civil Defence also advised people to stay away from open areas, windows, balconies and rooftops, while those outdoors were building or take shelter behind a solid barrier. Motorists receiving an alert were instructed to pull over away from bridges and high-rise buildings, while the public was urged to avoid gatherings and dangerous areas and follow instructions through official channels.

Read More:Saudi Arabia warns of 'firm' response after Houthi missile, drone attacks injure 13 civilians. The Houthi advances in recent ​days, including the taking of Perim Island at the mouth of the Red Sea, have put further pressure on Saudi oil exports after an aerial attack on Thursday knocked Saudi ​Arabia's east-west pipeline offline.

Riyadh blamed the pipeline attack on Iranian-backed militias in Iraq. Saudi Arabia built the 1,200-kilometre (745-mile) pipeline across its territory from the Gulf ⁠to the Red Sea in the 1980s to bypass the Strait of Hormuz when it came under threat from the Iran-Iraq war at that time.

Traders said a prolonged shutdown of the Saudi pipeline ​could cut off as much as 4% of global oil supply while the strait is largely blockaded. Riyadh has not said when operations might resume.

Responding to the Houthi offensive, the Saudi and Yemeni air forces have stepped ​up aerial bombardment of Houthi targets, including around the historic Red Sea port of Mocha, but the Houthis have maintained effective control over almost the entire western coast of the country along the Red Sea, the officials with Yemen's internationally recognised government said.

“The Houthis are being put under heavy pressure. They in turn are putting more and more pressure on the Saudis, increasing their campaign of missile and drone attacks,” one of the Yemeni officials said.