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.
According to the cables, which date between 2007-09, Husseini said Saudi Arabia might reach an output of 12m barrels a day in 10 years but before then - possibly as early as 2012 - global oil production would have hit its highest point. This crunch point is known as "peak oil".
Husseini said that at that point Aramco would not be able to stop the rise of global oil prices because the Saudi energy industry had overstated its recoverable reserves to spur foreign investment.
One of the cables said: "According to al-Husseini, the crux of the issue is twofold. First, it is possible that Saudi reserves are not as bountiful as sometimes described, and the timeline for their production not as unrestrained as Aramco and energy optimists would like to portray."
It went on: "Al-Husseini disagrees with this analysis, believing Aramco's reserves are overstated by as much as 300bn barrels. In his view once 50% of original proven reserves has been reached … a steady output in decline will ensue and no amount of effort will be able to stop it. He believes that what will result is a plateau in total output that will last approximately 15 years followed by decreasing output."