The spike in US petrol prices over the last few weeks has been driven largely by speculation and unregulated trading in crude oil, according to the Foundation for Taxpayer and Consumer Rights's Oilwatchdog project.

With the price of a barrel of crude oil hitting another new record above $93, petrol prices are also at a record level for this time of year, said the Foundation for Taxpayer and Consumer Rights (FTCR) in a press release. The average US price of regular petrol is at $2.872 a gallon, up from $2.762 on October 15, 2007, said the FTCR, citing the federal Energy Information Administration.

Judy Dugan, research director of FTCR and its Oilwatchdog project, said: Speculators in largely unregulated futures markets are using any excuse, from bad weather in Mexico to a dip in US oil supplies, to drive crude oil toward $100.

The organization supports a Senate bill, the Oil and Gas Traders Oversight Act, by California senator Dianne Feinstein, which it says would add transparency and federal oversight to unregulated futures markets in energy.

The FTCR noted that oil companies and their refiners do not pay the spot price for most of the crude oil that they process into petrol, diesel and heating oil.