The chief executive of the Swiss watchmaker Swatch Group, Nick Hayek, gives a press conference in 2011. The world's biggest watch company is looking at building a car that runs on hydrogen and oxygen, Hayek said in an interview published Sunday.

The world's biggest watch company Swatch is looking at building a car that runs on hydrogen and oxygen, its chief executive and chairman Nick Hayek said in an interview published Sunday.

"We already have a test-car with a fuel cell," Hayek told newspaper NZZ am Sonntag.

" and oxygen are used as fuel, producing very efficient ," he said, adding that the management board of Belenos -- the Swatch subsidiary building the vehicle -- has already driven around on the prototype.

"What we don't know is whether it would be cost-efficient to build," said Hayek, the son of Swatch's founder.

The fuel-cell vehicle is not Swatch's first attempt at building a . In 1997, it teamed up with Daimler-Benz to build the two-seater Smart but the watch firm later sold its shares to Daimler-Benz.