The European Court of Human Rights said on Monday it could not consider complaints over Russia's investigation into the 1940 Katyn massacre.
In a majority ruling, the judges said the killing took place before Russia ratified the European Convention on Human Rights, which allows citizens to appeal to the Strasbourg Court.
The case was brought by 15 Polish nationals who are relatives of 12 victims of the massacre, in which more than 20,000 members of the Polish elite were killed by Soviet secret police.
The ruling, which is not final, said Russia had "taken most of the investigative steps" before it ratified the Convention in 1998, and that no "important procedural steps" had taken place after that date.
There was also no "genuine connection between the deaths and the entry into force of the Convention," the court said.
However, the seven European judges said Russia did not fully collabortate with the court and failed to notify the court of its 2004 decision to discontinue the investigation.
The Russian authorities also failed to provide 10 relatives of the massacre's victims with "any official information about the circumstances surrounding the deaths, nor made any serious attempts to locate the burial sites of the relatives."
The court ordered Russia to pay the applicants jointly 5,000 euros in compensation.
The applicants' lawyer, Ireneusz Kamiński, said he was not "fully satisfied" with the ruling and would appeal the decision.
Late Polish President Lech Kaczynski and scores of other senior Polish figures were killed in a plane crash in April 2010 as they travelled to a memorial ceremony for the victims of the killing.