This announcement comes after the Kommersant daily reported that some manufacturing problems had been discovered. Russia had plans to launch 27 rockets this year.
The last time Russia launched a rocket was last year in October when the Soyuz MS-02 spacecraft was launched with a crew of one American and two Russian Astronauts for a two-day journey to the International Space Station. The launch took place in Baikonur Cosmodrome, Kazakhstan.
"Additional tests (on the Proton-M) are being carried out. That explains the possible delay in launches," said a spokesman for Roscosmos.
No further details were provided, but according to Kommersant daily, the problems were found in some components that had been used to develop the engine. According to the article, some parts were discovered not to be sufficiently heat resistant.
In December an unmanned cargo ship carrying supplies for the International Space Station, fell apart six minutes after lift-off. No explanation was provided for the mishap.
Kremlin spokesman Dmitry Peskov downplayed the delays, saying that although they had encountered a few hiccups, Roscosmos, had achieved a lot and the launches would take place eventually.
A spokesperson for Roscosmos, Igor Burenkov said that after the tests were done, then it would be determined how long the launch would be delayed for.