Global car makers such as Toyota and General Motors are developing environmentally friendly vehicles, under pressure to reduce harmful emissions produced by their cars amid fears of global warming.

"We will start mass production of a fuel cell model, like the i-blue, from 2012 at the earliest, or from 2015 at the latest," a Hyundai official said, asking not to be identified. He declined to provide price details, sales targets or development costs.

Hyundai unveiled "i-blue", the fuel cell CUV (crossover utility vehicle), at the Frankfurt International Motor Show earlier this month.

Hyundai, the world's No.6 car maker by sales volume along with its affiliate Kia Motors, plans to start in 2010 mass production of a hybrid model -- the Elantra compact car, according to the official.

Fuel cells use the interaction between hydrogen and oxygen to generate electricity to power a car while emitting only water but they have to yet become commercially viable.

Proponents insist that 5 million to 10 million fuel cell cars could be on the road within 15 years, with the number growing to 350 million worldwide by 2050.

But while the technology is making great strides, it still costs far too much and lacks the widespread infrastructure that motorists will need to fill their tanks with hydrogen.