A Proton M booster rocket with three Glonass M navigation satellites blasted off from the Baikonur space center on Monday in this year's final launch, a spokesman for Russia's space agency said.

"The launch was made at 13:38 Moscow time [10:38 GMT], with the spacecraft set to detach from the booster rocket at 17:10 Moscow time [14:10 GMT]," a Roscosmos spokesman said.

The 18 satellites that the Glonass system requires for continuous navigation services covering the entire territory of Russia are currently in orbit.

Another six satellites still have to reach 24, the number needed to provide services worldwide.

Roscosmos chief Anatoly Perminov earlier said that of the six remaining satellites three would be launched in December, with the other three launches put off until February 2010.

A total of 9.9 billion rubles ($360 million at the current exchange rate) was allocated for Glonass from the federal budget in 2007, and 4.7 billion rubles ($170 million) in 2006.

Putin signed an order on September 12, 2008, providing an additional $2.6 billion to develop the system.

MOSCOW, December 14 (RIA Novosti)