Unmanned spacecraft is due to crash back to Earth on Friday

Russian: An unmanned Russian spacecraft that failed in its mission to deliver three tons of supplies to the International Space Station is due to crash back to Earth on Friday.

The Progress capsule is expected to re-enter the atmosphere at 9am, according to US Air Force tracking data.

The capsule and cargo are expected to burn up in the atmosphere, with any surviving debris likely to land in the ocean.

The probe blasted off from Kazakhstan on April 28 loaded with three tons of fuel and food.

But flight controllers lost contact with the craft shortly after it reached orbit and radars showed the capsule was tumbling back to Earth.

The cause of the accident is under investigation and results are due next week.

The Air Force's Joint Space Operations Centre, which tracks satellites and junk orbiting Earth, found 44 pieces of debris near Progress, possibly indicating that an explosion or other problem occurred when the craft separated from its booster rocket.

Russian space agency Roscosmos said: "Only a few small pieces of structural elements could reach the planet's surface."

The exact location where Progress will re-enter the atmosphere is not yet known.

Dozens of spacecraft larger than Progress have made safe through uncontrolled returns into Earth's atmosphere, including the United States' 152,000 pound (69,000 kg) Skylab space station in 1979 and Russia's 29,800 pound (13,500 kg) failed Phobos-Grunt Mars probe in 2012.