Simmons said it was not just national oil companies, but also oil majors, including ExxonMobil, BP and Royal Dutch Shell, who should be providing precise data to establish the health of the world's supplies once and for all.

"In my opinion the only way to reliably gauge the timing of the peak is to stipulate a legal requirement for any field producing over 50,000 barrels per day to produce historical data on a quarterly basis," Simmons said on Tuesday in a speech as part of International Petroleum Week.

Data so far in existence are sketchy, with the exception of for the British and Norwegian North Sea, Simmons said.

He noted members of the Organization of the Petroleum Exporting Countries, led by Saudi Arabia, have never allowed an independent audit of their reserves.

"The world is basing its energy future on a non-audited set of books," he said.

It was not just the secretive oil nations, but also the oil majors who needed to produce the field-by-field data, Simmons told reporters after his speech.

"If they did that, they would learn a lot about why they have been off for the last few years about their data."

Many in the oil industry have disputed Simmons's theories, arguing technology and non-conventional sources of oil, such as Canadian tar sands, will help to ensure supplies for years to come.

But Simmons said such optimism had no basis in fact.

He said so far supplies of crude oil had not exceeded a peak of just over 74 million barrels per day (bpd) in 2005, citing US government figures.

Oil supplies, including condensates and fuel from non-conventional sources, are running at around 85 million bpd.

Simmons also warned of a possible decline in gas as well as oil.

"Natural gas statistics are far fuzzier than oil, but the litany of data suggests gas may be declining too," Simmons said, adding that gas declines far more rapidly than oil.