Virgin Galactic insists safety has always been central to its operations, following the crash of its experimental spacecraft in the US on Friday.

SpaceShipTwo broke up in mid-air during a test flight in California's Mojave Desert, killing one of the two pilots.

Virgin Galactic hopes to sends tourists on suborbital flights.

An investigation into the crash could take about a year, the head of America's National Transportation Safety Board (NTSB) has said.

'Time to focus'

In a statement responding to criticism in the media about its approach to safety, Virgin Galactic said "everything we do is to pursue the vision of accessible and democratised space - and to do it safely".

It added: "Just like early air or sea travel, it is hard and complicated, but we believe that a thriving commercial space industry will have far reaching benefits for humanity, technology and research for generations to come.

"Now is not the time for speculation. Now is the time to focus on all those affected by this tragic accident and to work with the experts at the NTSB, to get to the bottom of what happened on that tragic day."

Virgin Galactic founder Sir Richard Branson has said he is "determined to find out what went wrong" and learn from the tragedy.

NTSB head Christopher Hart said on Sunday that the agency would be examining evidence at the scene for four to seven days.

He said the craft's debris was spread over an area measuring five miles (8km) from end to end.

He told a news conference the test flight had been "heavily documented" and his team would have to trawl through "extensive data", which was why the full investigation could take "about 12 months or so".

He said there were six cameras on the craft itself, with another three on its launcher, an aircraft called WhiteKnightTwo, although it was unclear whether SpaceShipTwo's cameras had been found.

Source: BBC