0959 GMT October 15, 2019
Huge palls of smoke rose into the sky after the predawn attacks on Abqaiq and Khurais, two major Aramco facilities in eastern Saudi Arabia.
The attacks highlight how the increasingly advanced weaponry of Yemen’s Houthi movement – from ballistic missiles to unmanned drones – poses a serious threat to oil installations in Saudi Arabia, the world's top crude exporter.
"At 4:00 a.m. (0100 GMT) the industrial security teams of Aramco started dealing with fires at two of its facilities in Abqaiq and Khurais as a result of... drones," The Interior Ministry said in a statement.
"The two fires have been controlled."
The statement added that an investigation had been launched after the attack in the kingdom's Eastern Province, but did not specify whether operations at the two facilities had been affected.
Interior Ministry spokesman Mansour al-Turki said there were no casualties.
But the full extent of the damage was not immediately clear as reporters were not allowed near the plants, where Saudi authorities appeared to have beefed up security.
Earlier verified video footage showed bright flames and thick plumes of smoke rising toward the dark predawn sky.
The Houthi military spokesman said the attacks hit refineries at both sites, which are over 1,000 kilometers from the Yemeni capital Sana’a, and pledged a widening of assaults on Saudi Arabia.
In recent months, Yemeni forces have carried out a spate of cross-border missile and drone attacks targeting Saudi airbases and other facilities in what they say is retaliation for a long-running Saudi-led bombing campaign on Yemen.
The Houthis launched "a large-scale operation involving 10 drones that targeted refineries in Abqaiq and Khurais in eastern Saudi Arabia", the group's Al-Masirah television reported.
The Saudi-led coalition launched airstrikes on Yemen’s northern Sa’ada Province, a Houthi stronghold, on Saturday. Al-Masirah said the warplanes targeted a military camp north of Sa’ada city.
Last month, an attack claimed by Houthi forces sparked a fire at Aramco's Shaybah natural gas liquefaction facility – close to the Emirati border – but no casualties were reported by the company.
Yemeni drones also targeted two oil pumping stations on Saudi Arabia's key east-west pipeline in May, shutting it down for several days.
The growing attacks underscore how Saudi infrastructure, including oil installations, are increasingly vulnerable to retaliatory attacks four years after a Saudi-led coalition launched an air campaign against Yemen.
The Abqaiq facility, 60 kilometers (37 miles) southwest of Aramco's Dhahran headquarters, is home to the company's largest oil processing plant. Khurais, 250 kilometers from Dhahran, hosts a major Aramco oil field.
Riyadh had hoped for a quick win against the Houthis, but instead waded into a quagmire that has cost it billions of dollars and tarnished its reputation, while devastating the Arab world's poorest country.
The latest attacks come as Saudi Arabia accelerates preparations for a much-anticipated initial public offering of Aramco, the world's most profitable company.
Aramco is ready for a two-stage stock market debut including an international listing "very soon", its CEO Amin Nasser told reporters on Tuesday.
AFP and Reuters contributed to this story.