The unmanned SpaceX Falcon-9 rocket, designed to carry supplies to the International Space Station, has exploded minutes after it was launched in Florida, NASA has said.

Sunday's incident occured approximately two and a half minutes after lift-off from Cape Canaveral in the US state.

With more than 5,200 pounds of space station cargo on board, including the first docking port designed for future commercial crew capsules, the 63-metre rocket was SpaceX's 19th Falcon 9 launch since its 2010 debut.

Pieces of the rocket could be seen falling into the Atlantic.

SpaceX, a private company, was contracted in 2006 by NASA to design and demonstrate a launch system to resupply cargo to the ISS

In a statement, NASA said that the failure was caused by "an overpressure event in the upper stage liquid oxygen tank".

"The astronauts are safe aboard the station [ISS] and have sufficient supplies for the next several months," it said.

"We will work closely with SpaceX to understand what happened, fix the problem and return to flight."

A couple of minutes after the explosion, NASA had tweeted that "space is hard".

Al Jazeera