The fuel, believed to be red diesel, was stolen sometime overnight between Thursday (November 7) and Friday (November 8),
PC Kev Berry, from Poulton and Over Wyre Neighbourhood Policing Team, said: "A white van is believed to be responsible for stealing approximately 100 litres of fuel.
"Please be vigilant and if you do see anything in the Garstang and Over Wyre area, please contact Police immediately through the usual channels."
Red diesel is a fuel used to run off-road vehicles, particularly tractors.
It is the same as standard road diesel – known as white diesel – but attracts around 40 per cent less fuel duty, meaning it is significantly cheaper to buy.