A US company says it will have a nuclear-powered prototype vehicle on the road within two years.

Laser Power Systems from Connecticut is developing a method of propulsion that uses thorium to produce electricity to power a car engine.

Thorium is an element similar to uranium and because it is such a dense material it has the potential to produce massive amounts of heat.

According to Laser Power Systems CEO, Charles Stevens, just one gram of thorium produces more energy than 28000 litres of petrol. Mr Stevens says just eight grams of thorium would be enough to power a vehicle for its entire life.