An investigation into the fatal Virgin Galactic spaceship crash has found the function to help it descend was deployed early.

Christopher Hart, the head of the National Transportation Safety Board, said the craft's fuel tanks and engine had been recovered intact - indicating there was no explosion.

Mr Hart said: "Normal launch procedures are that after the release, the ignition of the rocket, and acceleration, the feathering devices are not to be moved.

"The lock/unlock lever is not to be moved into the unlock position until the acceleration is up to Mach 1.4. Instead, as I indicated, that occurred at approximately Mach 1.0."

Camera footage from inside the vehicle showed the lock/unlock lever was moved by one of the pilots.

But Mr Hart stressed he was not saying this had been the cause of the disaster, and was simply providing a statement of fact.

Nearly all the important parts of the vessel had been recovered and had been taken to a hangar for examination.

He told reporters the fuel tanks and engine showed no signs of "burn through" or being breached.

SpaceShipTwo exploded over California's Mojave Desert during its 35th test flight shortly before being released at high altitude from its mothership WhiteKnightTwo.

Pilot Michael Alsbury, 39, from Tehachapi, California, was killed in Friday's crash.

Fellow pilot, Peter Siebold, 43, was badly injured after ejecting.

Virgin Galactic had been aiming to become the first commercial "spaceline", by beginning tourist flights to the edge of space next year.

Justin Bieber, Ashton Kutcher, Brad Pitt and Angelina Jolie are among those who are said to have already reserved seats and paid a deposit on the $250,000 (£156,000) ticket price for a minutes-long suborbital flight on SpaceShipTwo, which could carry six passengers.

Sir Richard Branson said none of the 700 ticket holders had so far backed out.

The Virgin Group founder said one person had actually bought a ticket since the crash.