Reuters news agency reported earlier that the number of casualties among Russians in Syria was much higher in comparison with the officially provided figures.
"No, they will be not," Peskov said replying to a question whether official figures would be double-checked, TASS news agency reported.
"All information (for Kremlin) comes directly from the Defense Ministry and we have to accept these figures and they are official."
"There may be Russian nationals in Syria staying there as volunteers or for some other purposes, but they have nothing to do with the government and the Defense Ministry," he said. "In this case one should inquire with Reuters about where they obtained this information and who the source was."
According to Reuters, a total of 40 Russian nationals were killed in conflict-hit Syria since the beginning of the year and some of the casualties from the list were allegedly mercenaries.
The Defense Ministry maintains that the number of killed among the Russian Armed Forces, deployed in Syria to provide assistance to the country’s military, stands at 34.