The confidential cables, made public on the WikiLeaks Web site, warned Washington a Saudi government oil executive had said Saudi oil reserves may have been overstated by as much as 40 percent, or a whopping 300 billion barrels.
Britain's The Guardian said Tuesday subsequent cables warned Saudi oil monopoly Aramco was "having to run harder to stay in place" and questioned Saudi Arabia's ability to keep the world supplied with enough crude to keep a lid on prices over the long term.
The WikiLeaks cables detailed a 2007 meeting between the U.S. consul general in Riyadh and Sadad al-Husseini, the former head of exploration for Aramco.
"According to al-Husseini, the crux of the issue is two-fold," the cable to Washington said. "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."
Al-Husseini took issue with an official Aramco projection in 2007 that the company had 716 billion barrels in reserve and would increase that stockpile to 900 billion barrels in about 20 years.