A Russian Mars probe trapped in a decaying orbit will most likely hit Argentina on Sunday, the Interfax news agency reported, citing an unnamed official at Russian national space agency Roscosmos.

Debris from the 13.5-ton space vehicle has the greatest chance of striking some 120 kilometres to the west of the Argentinian city of Rosario at 9:52 pm Moscow time (1752 GMT), the report said.

The Phobos-Ground probe has been circling Earth and refusing to respond to ground commands since mid-December, when its interplanetary engines failed to ignite after a normal launch.

More than 80 per cent of the spaceship’s mass is rocket fuel, which will burn up passing through the Earth’s atmosphere, but some 20-30 pieces of the probe may survive re-entry and reach the Earth’s surface, Roscosmos officials have said.