The scale of any energy price rises, and the wider impact, will depend on the magnitude of what comes next in the conflict between Israel and Iran. But it does have the potential to be "a bad shock for the global economy at a bad time" says Mohammed El-Erian, chief economic adviser at asset manager Allianz.

The move was interpreted as an attempt to ratchet down hostilities after the U.S. military action against Iran’s nuclear facilities.