The Russian Space Agency says a Proton M rocket carrier has crashed over the east of Russia, just minutes after being launched from Kazakhstan.
The Mexican satellite it was transporting is missing, presumed lost.
Russian news agencies say the third stage of the rocket malfunctioned some 500 seconds after take-off and came down in the Chita region of Siberia.
It was carrying a telecommunications satellite – manufactured by Boeing on behalf of the Mexican government – which was supposed to have been launched into orbit. There are now fears hazardous chemicals from the failed launch may have leaked into the atmosphere. An investigation is underway.
It is the second space-related problem in 24 hours. A Progress M-26M spaceship, which is docked at the International Space Station, has “failed to ignite its engines and correct the orbit of the space outpost,” Russian media reports.