Yemen's Iran-aligned Houthi group attacked two plants at the heart of Saudi Arabia's oil industry, including the world's biggest petroleum processing facility, in a pre-dawn strike that several sources said had disrupted output and exports.
"Totally unacceptable attack on oil facilities in Saudi Arabia this morning," Andrew Murrison, the British foreign affairs minister responsible for the Middle East and North Africa said on Twitter.
"The Houthis must stop undermining Saudi Arabia's security by threatening civilian areas and commercial infrastructure," Murrison added.