The US fears that Saudi Arabia, the world's largest crude oil exporter, may not have enough reserves to prevent oil prices escalating, confidential cables from its embassy in Riyadh show. The cables, released by WikiLeaks, urge Washington to take seriously a warning from a senior Saudi government oil executive that the kingdom's crude oil reserves may have been overstated by as much as 300bn barrels—nearly 40%. The revelation comes as the oil price has soared in recent weeks to more than $100 a barrel on global demand and tensions in the Middle East.