Elon Musk, the CEO of SpaceX (www.spacex.com), has said that the explosion of his company’s Falcon 9 rocket last month was caused by a failed support piece (or strut).

Speaking to reporters on a conference call about the 28 June failure of what was meant to be a routine cargo mission to the International Space Station, Mr Musk said: “One of the struts broke free, resulting in a helium bottle shooting to the top of the rocket’s liquid-oxygen tank at high speed.”

The accident saw NASA lose equipment worth $110 million that was bound for the ISS. A SpaceX spokesman later said: “There are several hundred struts on every Falcon 9 vehicle. The one that we believe failed was designed and material-certified to handle 10,000lb of force but failed at 2,000lb — a five-fold difference.

Detailed photos of stage construction show no visible flaws or damage of any kind. The struts in question are each two feet long and an inch thick; they came from an outside supplier.

We are not going to use these particular struts in the future.” Mr Musk has said that SpaceX will return to flight with the Falcon 9 “no sooner than September.”

He also said that the problem is not expected to delay the company’s goal of sending astronauts into space aboard its Dragon spaceship within the next two years.