US blames Iran for Saudi oil attack

US president Donald Trump said the United States was "locked and loaded" for a potential response to the attack on Saudi Arabia's oil facilities, after a senior US administration official said Iran was to blame.

Trump also authorized the use of the US emergency oil stockpile to ensure stable supplies after the attack, which shut 5% of world production and sent crude prices soaring more than 19% in early trade on Monday, before moderating to show a 10% gain.

"There is reason to believe that we know the culprit, are locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack, and under what terms we would proceed!" Trump said on Twitter.