MOSCOW, December 25 (RIA Novosti) - Russia successfully orbited at 10:42 p.m. Moscow time (7:42 p.m. GMT) on Tuesday three Glonass navigation satellites, a spokesman for the Federal Space Agency (Roscosmos) said.

The three satellites were launched from the Baikonur space center in Kazakhstan to join the existing satellite constellation, which comprises 15 operational satellites. The launch took place for the first time on board an improved Proton-M carrier rocket.

"The DM upper-stage rocket and three Glonass satellites separated from the booster rocket and went into orbit," the spokesman said.

The satellites are scheduled to separate from the upper-stage rocket at 2:24 a.m. Moscow time (11:24 p.m. GMT).

This was the second successful launch of a Proton rocket carrying Glonass navigation satellites this year. A previous launch of a Proton-M carrier rocket on September 6 failed.

Glonass (Global Navigation Satellite System) is the Russian equivalent of the U.S. Global Positioning System (GPS), which is designed for both military and civilian use, and allows users to identify their positions in real time.