President Donald Trump has been browbeating his Gulf ally for weeks to prevent a jump in petrol prices. This he week praised Saudi Arabia’s leadership for its role in the 30 per cent slide in oil prices over the past two months, in which Brent crude dropped from $86 a barrel to a low of $58.41 on Friday.

Saudi leaders have been discussing the need to cut output, as a price collapse threatens its budget. But traders said Mr Trump’s support for Crown Prince Mohammed bin Salman in the wake of the killing of journalist Jamal Khashoggi would complicate decision-making in Riyadh.