The Russian Federal Space Agency in a statement today described the accident as a malfunction and said it was looking into what had happened. Russian news agencies quoted authorities in eastern Siberia as saying they are searching for the third stage of the rocket, which is believed to have crashed there.
The rocket, Proton-M, was launched from the Russia-leased Baikonur cosmodrome earlier on Saturday. Proton-M has a history of mishaps, leading to the loss of three navigation satellites last year.
Observers say post-Soviet Russia's space program has been hampered by a brain drain and a steady erosion of engineering and quality standards.