Russia will launch another three Glonass-M satellites on board a Proton heavy carrier rocket later this year to complete the orbiting Glonass grouping, the head of Russia's space agency Roscosmos said Tuesday.

Anatoly Perminov told a news conference in Moscow that Roscosmos allocated about 3 billion rubles ($100 million) for the launch, expected in May-June.

The recent loss of three Glonass-M satellites as a result of a series of mistakes made by the Russian Energia rocket corporation cost Russia 2.5 billion rubles ($82 million) in direct damages.

The December 5 launch of the Proton-M carrier rocket was supposed to conclude the forming of Russia's Glonass navigation system, a project similar to GPS in the United States.

However, the rocket veered off course and sunk in the Pacific Ocean.

Russia has switched on two reserve Glonass-M satellites in orbit to compensate for the ones that were lost. Roscosmos will also launch a Glonass-K satellite in Feb.-March to bring the current number of operational satellites in orbit to 23.

The complete grouping must have 24 operational and 2-3 reserve satellites for Glonass network to operate with global coverage.