A space safety expert says she warned Virgin about safety concerns after the deaths of three engineers in a rocket engine explosion in 2007.

"I warned them that the rocket motor was potentially dangerous," said Carolynne Campbell, a rocket propulsion expert at the Netherlands-based International Association for the Advancement of Space Safety (IAASS).

"We were concerned about what was going on at Virgin Galactic and that what they were doing wasn't up to speed," she said.

The accusation comes only days after Virgin Galactic SpaceShipTwo crashed in the Mojave Desert in California killing 39-year-old pilot Michael Alsbury and injured 43-year-old Peter Siebold. http://www.abc.net.au/news/2014-11-03/virgin-wasnt-up-to-speed-and-warned-about-safety/5861512

Branson's Virgin Galactic accused of ignoring warnings that spaceship was unsafe to fly

Sir Richard Branson's space tourism company Virgin Galactic has been accused of ignoring a series of warnings that its $US500 million rocket was unsafe for flight.

A number of senior aerospace engineers repeatedly voiced fears over the design of Sir Richard's SpaceShipTwo and the safety protocols surrounding its testing.

London's The Sunday Telegraph reported it has seen emails and other documents in the public domain - dating back several years, and as recently as last year - in which the engineers warned of the dangers of Virgin Galactic's rocket engine system.

It also emerged that three senior Virgin Galactic executives - the vice-president in charge of propulsion, the vice-president in charge of safety, and the chief aerodynamics engineer - had all quit the company in recent months.

http://www.msn.com/en-au/news/world/bransons-virgin-galactic-accused-of-ignoring-warnings-that-spaceship-was-unsafe-to-fly/ar-BBcrKhW

Virgin Galactic crash: Branson 'should stick to mobile phones' says expert

Ms Campbell said she sent multiple warnings to Virgin since 2009