FACTBOX: Peak oil: Fact or fallacy?

(Reuters) - The price of crude oil has hit record levels above $135 a barrel, pushing industry analysts to take more seriously peak oil, or the idea that global production is near an apex after which it will decline sharply.

The following are some facts about the concept, its adherents and its detractors.

- The theory of peak oil was first suggested by geoscientist Marion King Hubbert, who in 1956 predicted U.S. oil production would peak between 1965 and 1970.

Figures from the U.S. government Energy Information Administration show crude oil production peaked in the United States in 1970.

The Hubbert peak curve is a bell-shaped model of production for a particular country, region or the world, given an assumed total recoverable volume.

The theory has long been considered marginal, and premature declarations and inaccurate predictions have weakened its credibility.

- Output of oil world-wide is 86 million barrels per day (bpd) and will rise to 116 million bpd by 2030, according to the International Energy Agency (IEA), whose forecasts are a benchmark for the oil industry.

The strong growth in demand from developing countries, such as China and India, is also likely to continue in that period.

- Some oil majors acknowledge the prospect of dwindling production, while others maintain better extraction techniques and other advances will offset any decline.