Houthi missile and drone attacks have targeted several Saudi Arabian towns this week, injuring more than a dozen people in the south as the Iranian-backed movement keeps up a days-long assault on the kingdom that has jolted oil markets and opened a new front in the Middle East conflict.

In a sign of Riyadh attempting to demonstrate "business as usual", Mohammed bin Salman went ahead on Tuesday with a long-planned state visit to Egypt to meet President Abdel Fattah al-Sisi. The two leaders committed to ensuring freedom of navigation through the Strait of Hormuz, the Bab al-Mandeb Strait and the Red Sea, Egyptian state media said.

But Riyadh is facing a deepening crisis as the Houthis have dragged the kingdom back into conflict, while an attack by Iranian-aligned militants in Iraq last week forced Saudi Arabia to shut its East-West oil pipeline. According to Saudi military spokesman Major General Turki al-Malki, the Houthi attacks targeted the Saudi towns of Abha and Taif as well as Khamis Mushait, wounding 13 civilians and damaging seven houses.

The multiple attacks on Saudi Arabia, the world's top oil exporter, and the Houthis' advance along the Red Sea coast have pushed up crude prices to their highest levels since mid-May. They have also shattered a four-year ceasefire between Saudi Arabia and the Houthis that had brought relative calm to Yemen's civil war.