A Russian Proton-M rocket blasted off on Tuesday carrying three new satellites for Moscow's GLONASS navigation system, Interfax cited a spokesman for Russia's space agency as saying.

Sixteen satellites are already in orbit for GLONASS, developed in the 1980s by the Russian military and a competitor system to the US Global Positioning System (GPS), Europe's Galileo and a Chinese programme.

The three new satellites were due to be placed in orbit at 2300 GMT, the spokesman told Interfax.

Ultimately GLONASS will include 24 satellites from 2009.