Russian daily Nezavisimaya Gazeta said an appeal filed by Yezhi Yanowitz and Antony Rybovsky, a son and a grandson of Polish officers killed in western Russia's Katyn forest in 1940, was earlier rejected by a Moscow court.
More than 20,000 Polish military officers, police and civilians taken prisoner during the 1939 partitioning of Poland by the Soviet Union and Nazi Germany were massacred by the NKVD, the forerunner of the KGB, in the Katyn forest and at other locations.
The newspaper said that the Strasbourg court's decision may have been taken due to the Moscow court's refusal last week to exonerate the Polish prisoners of war.
In 2005, the Chief Military Prosecutor's Office closed the "Katyn Case", saying those involved in the executions had since died. However, the relatives of the executed officers appealed the decision to close the case.
The Soviet Union initially accused Germany of executing the Polish prisoners. However, in 1990 Mikhail Gorbachev officially admitted that Soviet secret police were responsible for the massacre.