File picture: Michael Noble Jr / Reuters.

Formula One will come under pressure from electric car racing in the next five years and risks being overtaken in popularity further down the road, according to Formula E founder Alejandro Agag.

Speaking in a podcast interview with 2016 Formula One champion Nico Rosberg, who is also a shareholder in the electric series, Agag suggested Formula One was in danger of being left behind.

"I think in five years they are going to start feeling a lot the heat," said the Spaniard.

"I think in 10 years it’s going to be very difficult that they don’t switch to electric. But they can’t. But they will really feel the pressure to switch to electric.

"In 10 years electric cars will go as fast as combustion cars. So when you have these cars going as fast, what is the reason to stick to an old technology? you should move to a new technology.

"I think when the industry is electric, Formula E will happen to be the main motorsport in the world."

Formula E, like Formula One, is sanctioned by the International Automobile Federation (FIA) but has an exclusive licence for 25 years to be the sole electric championship.

Ross Brawn, Formula One's managing director for motorsport, said this year that he did not see the sport, currently reviewing its engine formula from 2021, locked into internal combustion engines forever.

The current V6 power units use hybrid energy recovery systems.

Agag also told Rosberg that Formula E almost folded in its debut season, with enough capital initially for only three races.

"At one point I owed $25 million to our suppliers and I had $100 000 in the bank, that was the situation," he said.

"We were actually really at the limit. I had to pay from my pocket the air freight of the cars to go to the Miami race."

John Malone's Liberty Global and Discovery Communications then bought a stake and others followed. Formula One's commercial rights holder is Liberty Media.

Separately, quoted Agag as saying he had dropped a $696.8 million attempt to take back full-ownership of the series.

"Liberty and Discovery don't want to sell," he said.