Nov 2 (Reuters) - Saudi Arabia's civil defence authority on Monday said the threat had passed shortly after issuing alerts for the southern and western cities of Khamis Mushait, Abha, Taif and Najran, amid weeks of escalating hostilities with Yemen's Houthis.

The Saudi-led coalition in Yemen later said it had intercepted and destroyed a ballistic missile launched by the Iran-aligned Houthis towards the southern region of Saudi Arabia.

Southern Saudi Arabia, which borders Yemen, has come under repeated Houthi missile and drone attacks targeting military installations and energy infrastructure, including Jazan, home to a 400,000-barrel-per-day oil refinery on the Red Sea coast.

Saudi Arabia has also carried out airstrikes against Houthi targets in Yemen, as the renewed fighting heightens risks to the kingdom's oil production and exports.

The Houthis have also targeted Saudi Arabia's East-West pipeline and oil export facilities in Yanbu, a key Red Sea outlet for Saudi crude shipments.

(Reporting by Nayera Abdallah; Writing by Jana Choukeir; Editing by Clarence Fernandez, Alexandra Hudson)