Large swathes of land is not suited to crops said the government

But a spokesman said the growing of energy crops will have to be balanced with demands for food security and protecting the environment.

Friends of the Earth Scotland also said biofuels will have a part to play in the future.

But the organisation said it had concerns about any impact on biodiversity.

The government spokesman said: "The Scottish Government is currently exploring how we can best exploit technologies in order that they make a real, sustainable and cost-effective contribution to transport carbon reduction, including the role of biofuels.

"In recent years we have committed �10.2m of investment in biofuel production in Scotland through RSA funding for Ineos' bio-diesel plant in Grangemouth and Argent's plant in Motherwell, and are participating in the UK Renewable Transport Fuel Obligation."

Although we are not a country in hunger, our priority still needs to be feeding people and not cars Friends of the Earth Scotland spokesman 'More could be grown'

He added: "Industry is already taking steps towards reducing transport emissions by increasing the fuel efficiency of new vehicles by means of conventional technology - and appropriate biofuel use can complement this.

"The EU is also working with all member states to support research and development into low carbon transport technologies.

"All of these activities, together with softer measures such as eco-driving and modal shift can contribute to our ambitious climate change target to reduce emissions by 80% by 2050."

The Scottish Government said energy crops were in their infancy in Scotland and it was keen to support farmers.

But it said production of oilseed rape was less than the 1.5m tonnes per year needed to feed the two Scottish bio-diesel plants due to come on stream in the next couple of years - DMF Biodiesel in Rosyth and Ineos in Grangemouth.

More than 80% of land was also estimated to be less favourable to growing energy crops.

Reducing demand

The Department for Environment, Food and Rural Affairs said the UK Government has already shown intentions towards "positive incentivisation" of carbon saving and sustainability for renewable fuels.

Friends of the Earth Scotland said it has three main concerns about biofuels - its impact on the environment, transport and displacing food crops.

A spokesman said: "If large amounts of set-aside land is converted to fuel-crops we could see a massive impact on biodiversity, where more set-aside land with rich eco-systems and wildlife is replaced with just one crop.

"Sometimes the crop needs to be transported very large distances for crushing and processing. Every mile it has to travel reduces the environmental benefits these fuels may have."

He added: "Although we are not a country in hunger, our priority still needs to be feeding people and not cars.

"Before we start producing large amounts of biofuels we need to work hard at reducing demand for transport fuel across the board.