Some customers who paid up to $250,000 for a ticket on the Virgin Galactic are reportedly looking for their money back, following the latest delay to the space rocket project.

Speaking on David Letterman’s TV show in the US, Richard Branson said the inaugural flight would now be delayed until “February or March or next year”, having previously planned to launch by the end of this year.

Owned by Sir Richard Branson’s Virgin Group and Abu Dhabi’s Aabar Investments, Virgin Galactic is set to become the world’s first commercial spaceline and claims to have already accepted more than $70 million in deposits from approximately 580 individuals.

According the Sunday Times newspaper, the latest delay led to claims that the project was in crisis with some customers questioning whether the rocket would ever reach 60 miles above the Earth, the internationally accepted boundary between the atmosphere and outer space, also known as the Karman line.

An unnamed customer, who had paid a deposit of $150,000, told Sunday Times: “I think it will fly, but I am not sure whether it will get me into space as I was promised. If they don’t get above 60 miles I will certainly be withdrawing my money. I don’t think you can be considered an astronaut unless you cross that line.”