A small British company which has produced the first “petrol from air” said yesterday it would refuse any investment offers from petrochemical companies because of fears the oil industry would take over the firm with the aim of closing it down.

Air Fuel Synthesis, a start-up operation based in Darlington, has been inundated with investment offers after The Independent reported it had made the first five litres of petrol from air at its small demonstration facility in Stockton-on-Tees.

The media furore over the breakthrough caused Nick Clegg, the Deputy Prime Minister, to make a short diversion yesterday on a trip to the town to see the demonstration plant for himself. "Maybe I really have glimpsed the future," Mr Clegg said.

Despite the interest in the breakthrough, however, the company's founder and principal investor, Professor Tony Marmont, said that he and his business colleagues would not want the oil industry to take a stake in the firm even though it is actively seeking investment partners to finance the next stage of development.

Professor Marmont, who used to work for Shell, put up half of the £1.2m used to set up the company. He said he was close to a deal with a major soft-drinks company interested in using the petrol to power its carbon-neutral vehicles.

"I would shudder at the prospect of an approach from the oil industry. My reaction would be 'I don't want to know' because I'd be fearful they would buy into the business and work to shut it down," he said.

"We've had calls offering us money from all over the world. We've never had that before. We've made the first petrol with our demonstration plant but the next stage is to build a bigger plant capable of producing one tonne of petrol a day, which means we need between £5m and £6m."

Air Fuel Synthesis produced the petrol by merging carbon dioxide from air with hydrogen from water using electricity from the National Grid, although it eventually intends to use a renewable source of energy.

The breakthrough was described as a "game changer" by the Institution of Mechanical Engineers (IMechE).

"I've been up there and seen it. It's a small pilot plant capturing air and extracting carbon dioxide from it," said Tim Fox, head of energy and the environment at the IMechE.

"It uses well-known and well-established components, but what is exciting is that they have put the whole thing together and shown that it can work. It sounds too good to be true, but it is true. The innovation is that they have made it happen as a process."