Private space travel company Blue Origin expects to launch its first human test flights in 2017, company founder Jeff Bezos has said.

The travellers would not be paying customers, he said, but thousands have expressed interest in paying for a trip on a suborbital craft.

For now, the man who founded is spending some of the billions earned from the Seattle-based online retailer on high-tech equipment and about 600 employees working in a former Boeing plane parts building.

Mr Bezos says he is convinced the company - a vision of his childhood dreams - will eventually be profitable.

The company is not taking deposits yet, so it is unclear whether thousands of interested space travellers will translate into sales.

Blue Origin, founded in 2000, has launched a ship twice and it landed safely. The company plans to keep testing until its usefulness is done then switch to other ships being built to test human flight.

The real money will be made selling rocket engines to others planning to launch satellites and spaceships, Mr Bezos said.

United Launch Alliance has asked Blue Origin to build the engine for its new launch vehicle so it can stop relying on Russian-made engines.

Mr Bezos, who still has his day job at Amazon, said he was deeply involved at Blue Origin and spends time in the Kent centre, about 17 miles south of Seattle, Washington. He enthusiastically shared technical details and explanations during a media tour and one engineer said he was as knowledgeable about the technology as anyone in the building.

"I only pursue things that I am passionate about," Mr Bezos said. He spoke of dreaming of space travel and building rockets since he was five.

He said he was not ready to share exactly how much he had invested in the space venture, saying just that all the high-tech equipment and about 600 employees added up to "a very significant number".

The media-shy company said welcoming the press to its development floor was a first step towards more openness, but all but a few photographs of the facility were banned.

Mr Bezos said he was not concerned about his competition to build the next generation of rocket engines because society would need lots of help moving industry and people off the planet.

A handful of other companies are currently competing in the private space business, including SpaceX and Virgin Galactic, which are also at the testing stage.

Mr Bezos does not care about being the first private company to offer space tourism to the masses. The real goal is to perfect their equipment by flying as many as 100 sub-orbital flights a year and Mr Bezos said safety was the number one goal.

The company also wants to eventually decrease the cost of space launches by enough to put projects like building a colony on Mars within reach. The key is making spaceships reusable, which is Blue Origin's goal, Mr Bezos said.

"What I know you cannot afford is throwing the hardware away," he said.