Virgin Galactic allegedly ignored warnings that its passenger spaceship, which crashed into the Mojave Desert, wasn't safe to fly, U.K. newspaper The Telegraph reported Sunday, citing emails and documents going back several years.
"This explosion is not a surprise. None whatsoever, I am sorry to say. It is exactly what I was expecting. It was Russian roulette which test flight blew up," Carolynne Campbell, the lead expert on rocket propulsion at the International Association for the Advancement of Space Safety (IAASS), said, according to the report.
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The report said she first warned Virgin Galactic about its nitrous oxide-propelled engines in 2007, after three engineers died during an explosion as the rocket was tested on the ground.
"Virgin Galactic is cooperating with an independent investigation by the National Transportation Safety Board (NTSB) and during that time we are not permitted to comment on the accident," the company said in an email to CNBC.
According to the Telegraph report, Branson said "I find it slightly irresponsible that people who know nothing about what they are saying can be saying things before the NTSB makes their comments."
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The craft exploded during a test flight on Friday at the Mojave Air and Space Port, killing one pilot and severely injuring another. The spaceship, which was undergoing its first powered test flight since January, suffered an "anomaly" soon after takeoff, officials said.
Friday's test was to be the spaceship's first powered test flight since January. In May, Virgin Galactic and spaceship developer Scaled Composites, a subsidiary of Northrop Grumman, switched to an alternative plastic-type of fuel grain for the hybrid rocket motor.
The crash is a major setback for Virgin Galactic, a U.S. offshoot of Branson's London-based Virgin Group. SpaceShipTwo, a six-passenger, two-pilot spacecraft is aiming to make the world's first commercial suborbital space flights.
Read the full story from The Telegraph.