Despite the discovery of massive new, untapped reserves, the world is much closer to running out of oil than official estimates show, claims a whistleblower at the International Energy Agency in the Guardian.

The unnamed source claims the US has been deliberately underplaying any potential shortage and, in effect, the IEA's annual Energy Outlook, expected to hold to previous estimates that oil production can be raised from its current level of 83m barrels a day to 105m barrels, is effectively bogus.

"Many inside the organisation believe that maintaining oil supplies at even 90m to 95m barrels a day would be impossible but there are fears that panic could spread on the financial markets if the figures were brought down further," the paper was told. "And the Americans fear the end of oil supremacy because it would threaten their power over access to oil resources."

Another IEA source, rejecting the agency's 2008 World Energy Outlook that oil output was "not expected to peak before 2030", said: "We have already entered the 'peak oil' zone. I think that the situation is really bad."

There are ominous signs in the market. Last week oil surged to $82 a barrel. Hardly the $140 mark it reach in August 2008 yet enough to affect a recovery. With inventories full and demand weak, estimations abound that it could go to $100 this winter.

Some analysts say the oil market is fundamentally over-supplied and cheap money is distorting prices, as it is other asset classes. But some will certainly argue that rising prices in the midst of a glut point to fundamental fears over long-term supply.

The Guardian's whistleblower claims a new "peak oil" is gaining support in the energy establishment. Back in 2005, IEA claimed suppliers could pump 120m barrels a day by 2030. "The 120m figure always was nonsense but even today's number is much higher than can be justified and the IEA knows this."

So when do we leave the oil age and enter the post-carbon age? Probably no one knows. A report by the UK Energy Research Council (UKERC) last month said worldwide production of conventionally extracted oil could "peak" and go into terminal decline before 2020. Last night John Hemming, the MP who chairs the all-party parliamentary group on peak oil and gas, said: "IEA figures cannot be relied on."