Poland's defence minister appeared to suggest the death of president Lech Kaczynski in a 2010 plane crash in western Russia was the result of foul play, an allegation that is likely to test already troubled relations with Moscow.
Antoni Macierewicz did not spell out who he suspected, but the comments were made in a passage of his speech referring to a number of events blamed on Russia, including the violence in shared neighbour Ukraine.
They also come at a politically sensitive time, months before Poland is due to host a Nato summit where it will push for the alliance to station more troops on its eastern flank to counter the newly assertive Russia.
An inquiry into Kaczynski's death by the previous government blamed pilot error. But Poland's new government, led by Kaczynski's twin brother Jaroslaw, has said an onboard explosion could have caused the crash. Though his party never openly accused Moscow of orchestrating the president's death, it has said the Kremlin benefited from it.
"I don't want to rule on whether ... political enemies of the current Russian authorities, who accuse (them) of reaching the highest positions by using armed terror against their own population, are right - perhaps it's not true," Defence Minister Macierewicz said in a lecture given at a conference on warfare and terrorism on Saturday.
"But there is no doubt that the (Russian) attack on Georgia was one that was first preceded by internal sabotage, inside of Georgia.
There's no doubt that what happened over Smolensk was aimed at depriving Poland of the leadership who led our nation towards independence."