Britain's foreign secretary Dominic Raab has condemned drone attacks on two Saudi oil plants as a "reckless attempt" to disrupt global oil supplies.
Yemen's Iran-aligned Houthi group claimed responsibility for attacking two Aramco oil refineries, causing huge fires on Saturday.
Dramatic footage showed a huge inferno engulfing the site in Abqaiq hours after the attack.
In a tweet on Sunday, Mr Raab said: "This was a reckless attempt to damage regional security and disrupt global oil supplies.
Just spoke to @SecPompeo about this egregious attack on the security of Saudi Arabia. This was a reckless attempt to damage regional security and disrupt global oil supplies. The UK condemns such behaviour unreservedly.— Dominic Raab (@DominicRaab)September 15, 2019
"The UK condemns such behaviour unreservedly."
He added he had earlier spoken to US Secretary of State Mike Pompeo about the attacks.
It comes after Iran dismissed accusations by the United States that it was behind attacks on Saudi oil plants that risk disrupting global energy supplies.
The country warned on Sunday that US bases and aircraft carriers in the region were in range of its missiles.
Yemen's Houthi group claimed responsibility for Saturday's attacks that knocked out more than half of Saudi oil output - or more than five per cent of global supply.
However, Mr Pompeo claimed the assault was the work of Iran, a Houthi ally.
Iranian foreign ministry spokesman Abbas Mousavi, speaking on state TV, dismissed the US allegation as "pointless".
The drone strikes on plants in the heartland of Saudi Arabia's oil industry, including the world's biggest petroleum processing facility, were expected to send oil prices up $5-10 per barrel on Monday as tensions rise in the Middle East.