Saudi Arabia’s oil production has been severely disrupted by drone attacks on two major oil facilities run by state-owned company Aramco, according to reports.
Saudi’s Energy Minister Prince Abdulaziz bin Salman said the strikes had reduced crude oil production by 5.7 million barrels a day – about half the kingdom’s output.
A Yemeni Houthi rebel spokesman said it had deployed 10 drones in the attacks.
US Secretary of State Mike Pompeo blamed the attacks on Iran saying there was no evidence they came from Yemen.
The fires are now under control at both facilities, Saudi state media say. Aramco CEO Amin Nasser said no casualties had been reported in the attacks.
The Saudis lead a Western-backed military coalition supporting Yemen’s government, while Iran backs the Houthi rebels.
In a tweet, Mike Pompeo described the attack as “an unprecedented attack on the world’s energy supply”.
“We call on all nations to publicly and unequivocally condemn Iran’s attacks,” Mr Pompeo added.
The US would work with its allies to ensure energy markets remain well supplied and “Iran is held accountable for its aggression”, he added.
Tensions between the US and Iran have escalated since Mr Trump abandoned a deal limiting Iran’s nuclear activities last year and reinstated sanctions.