He told a news conference: “I do want to caution the public…This is an accident site and it is a rocket. It had a lot of hazardous equipment, hazardous materials on board, that people should not be looking for or wanting to collect souvenirs over.”

Mr Culbertson added that anyone who finds anything should not touch it, keep others away from it and contact the local authorities.

No injuries were reported during the incident and the cause of the explosion is not yet known. NASA mission control in Texas called it a “catastrophic anomaly” – while engineers said the countdown had gone “according to plan” and there were no apparent issues with the machinery.

Nasa spokesman Rob Navias also claimed none of its cargo was needed “urgently” by the six astronauts on the ISS, which orbits 260 miles above the earth.

The rocket was carrying a Cygnus spacecraft packed with nearly 5,000lb (2,200kg) of food, supplies and materials for space experiments – including a nitrogen tank to manage the ISS’ air supply and some Maryland crab cakes for the space station crew.

The mission, known as CRS-3, was to be Orbital’s fourth trip to the ISS. Cygnus had been due to remain in orbit until November 2, when it would have flown itself to the station to allow astronauts to use a robotic crane to retrieve the capsule and its contents.

The rocket and cargo ship were valued at £123m, and were part of Orbital’s £1.1bn contract with NASA for a total of eight supply missions, following the retirement of the space agency’s own space shuttles.