Iran has accused the US of "deceit" after US Secretary of State Mike Pompeo said Tehran was behind damaging drone attacks on two Saudi oil facilities.
Pompeo had rejected claims by Yemen's Iran‑backed Houthi rebels that they had carried out the attacks.
Iran's Foreign Minister Javad Zarif said that "blaming Iran won't end the disaster" in Yemen.
Saudi Arabia said the strikes had halved its crude oil production to 5.7 million barrels a day.
All eyes will be on the markets when they reopen with experts expecting a significant rise in price.