The Moscow-based Kommersant newspaper claims citing a source in the Russian Defense Ministry that the last satellite of the Oko-1 ballistic missile attack early warning system has been lost.

In April, the 71XC satellite codenamed Cosmos-2479 stopped sending signals and became de-facto unmanageable, the source said, adding that attempts to reanimate it had failed. The same month the ministry ordered the satellite to be removed from combat duty.

The press service of the Lavochkin Research and Production Association, Russia's key satellite maker, declined comment, saying it was not authorized to discuss military programs. The spokespersons for the Russian Space Forces, when reached by the Kommersant, refused to elaborate on the satellite's current condition.

According to the newspaper, the satellite is worth more than 1.5 billion rubles, took about two years to create and had the expected service life of five-to-seven years. So far, of the eight early warning satellites launched by Russia since 1991, only two, Cosmos-2224 and Cosmos 2379, lasted longer than five years, the Kommersant says.

The previous 71X6 satellite (Cosmos-2440), launched in June 2008, went wrong in February 2010, the newspaper recalls. The loss of the satellites means that the Oko-1 system cannot function properly, the Kommersant concludes.

Oko-1 currently has two 73D6 satellites in high-elliptic orbits. They are operating normally. But the system requires six satellites to be able to fully perform its mission. As things stand now, it can only do it three hours a day, the source acknowledged.