Never has it been more profitable to grease the wheels of business by illicit means. Rocketing prices have prompted a rash of grease thefts from outside fast food joints.

The price of restaurant grease has risen more than tenfold over the past five years, driven by soaring demand for homemade biodiesel and high petrol prices.

The price of waste cooking oil reached £550 per tonne this month, according to Keith Coldrick, the managing director of Pelican Food Services, one of Britain's most established waste oil collection companies. That compares with about £50 per tonne in 2003.

Mr Coldrick said that high crude oil prices, which reached $146 per barrel this week, have led to an “absolute explosion” in demand for biodiesel, which can be easily processed from waste cooking oil for use in conventional diesel engines.

The rapid growth of the industry and the growing sums of money involved have led to a spate of thefts of waste oil drums from storage areas outside pubs and restaurants.

Pelican, based in Worcestershire, collects about 2,000 tonnes of waste oil annually from restaurants around the Midlands, including KFC.

“Barely a week goes by without a break-in at one of the stores in the area we collect from,” Mr Coldrick said. “The waste oil is usually kept outside in a fenced off area and often the door is just broken down in the middle of the night. It's happening all over the country.”

Small-scale kits for making biodiesel from waste cooking oil can be bought via the Internet for less than £1,000. “The people who sell this equipment lead their customers to believe that waste oil is easily obtainable, but it's not,” Mr Coldrick said. “The demand exceeds the supply.”

James Hygate, the managing director of Green Fuels - a retailer of home biodiesel kits based in Stonehouse, Gloucestershire, acknowledged that the theft of waste oil was a growing problem.

“The bigger waste oil collectors are feeling the cost of cooking oil thefts,” he said. “People are stealing drums of cooking oil that are being left outside and would normally be picked up by the big collectors.”

An estimated 200,000 tonnes of waste cooking oil are collected annually in the UK by about 80 established operators and “several hundred” smaller operators.

The figure has increased significantly as more and more restaurant operators realise its commercial value. Unscrupulous operators are being drawn to the business because of the growing sums of money involved and the ease with which they set themselves up in business.

A Waste Carriers Licence can be obtained from the Environment Agency for about £100. “They seem to hand them out to anyone,” Mr Coldrick said.

The price of waste cooking oil collapsed in Britain after new regulations banning its use in animal feed followed the outbreak of foot-and-mouth disease in Britain in 2001.

Since 2003, prices have rallied sharply as consumers have discovered its potential use as a vehicle fuel.

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