Ryad (AFP)

Saudi Arabia is trying on Sunday to restart its oil installations damaged the day before by drone attacks, which forced it to reduce its production, strategic for the world economy, by half.

Yemeni Houthi rebels, backed by Iran and who have been facing a military coalition led by Ryad for the past five years, have claimed responsibility for the attacks on state-owned Aramco's facilities.

Tehran, for its part, rejected the accusations of US Secretary of State Mike Pompeo, against the background of persistent tensions between the two enemies.

There is no evidence that "the unprecedented attack on global energy supplies" has come from Yemen, commented Mr. Pompeo on Saturday.

"The United States will work with its partners and allies to supply the energy markets and hold Iran accountable for its aggression," he added.

Tehran on Sunday ruled the charges "foolish" and "incomprehensible" by the spokesman of his Foreign Ministry, Abbas Mousavi.

He suggested that they were meant to justify "future actions" against Iran.

Saudi Crown Prince Mohammed bin Salman, whose country is Iran's great regional rival, assured that Ryad was "willing and able" to respond to this "terrorist aggression".

But James Dorsey, a Middle East expert at Singapore's S. Rajaratnam School of International Studies, has estimated that direct retaliation is unlikely. "The Saudis do not want an open conflict with Iran (...) They would like others to fight for them, but the others are reluctant," he said.

- Nervousness of the markets -

The Ryad Stock Exchange reacted to these attacks by falling by 3% at the opening of the transactions of the week, before taking back some of its losses.

Saturday's explosions sparked fires at the Abqaiq plant, the largest for oil processing in the world, and the Khurais site, which is home to a huge oil field.

Saudi Interior Ministry spokesman General Mansour al-Turki told AFP that the attacks had not resulted in any casualties.

And Saudi energy infrastructure had been affected many times by the Houthis.

But this strike is of another order: it caused a sharp reduction in production of 5.7 million barrels per day (b / d), or about 6% of global supply.

It could shake the confidence of investors looking to take a stake in Aramco, oil giant that is preparing a partial IPO.

The Saudi government hopes to raise up to $ 100 billion based on a $ 2 trillion valuation of the company, in what would then be the largest IPO in the world.

The operation was delayed several times due to, among other things, low oil prices.

As markets closely monitor Saudi Arabia's ability to contain the effects of the attack, Aramco CEO Amin Nasser said "work" was "under way" to restore full production.

Prince Abdel Aziz ben Salmane, newly appointed Minister of Energy, assured him that part of the decline would be offset by the use of large stocks.

Ryad, the world's largest exporter of crude oil, has built five gigantic underground storage facilities across the country that can hold tens of millions of barrels of various refined petroleum products.

- Vulnerable facilities -

In a telephone conversation between US President Donald Trump and the Crown Prince, the White House condemned attacks on "vital infrastructure for the global economy".

UN envoy to Yemen Martin Griffiths said he was "extremely concerned" by the attacks, which were quickly condemned by Riyadh's allies, the United Arab Emirates, Bahrain and Kuwait.

Paris also expressed "full solidarity with Saudi Arabia".

Although the kingdom's oil wells, scattered over vast areas, are hard to reach, its crude processing facilities are much more exposed.

In recent months, the Houthis have launched repeated cross-border missile and drone attacks targeting Saudi air bases and other facilities in what they describe as retaliation for Ryad's bombardment campaign against areas they control. in Yemen.

© 2019 AFP