He said Poland would issue a formal diplomatic note and summon the Russian ambassador in response.
Speaking at a press briefing in Brussels during an EU-Africa ministerial meeting on Wednesday, Sikorski said the memorial to Polish prisoners of war had been defaced in an act of "unacceptable interference in historical truth."
Some 6,300 Polish military and reserve officers, along with members of other state services, are buried at the Mednoye cemetery cemetery after being killed during World War II by the Soviet NKVD secret police as part of the 1940 Katyn Massacre.
'This was not done by vandals'
"The Virtuti Militari Cross and the 1939 Defensive War Cross were removed from the grave monument," Sikorski said, as cited by Polish state news agency PAP.
He added: "This was not done by vandals—it was carried out by the cemetery's administrators on orders from the local prosecutor’s office ... That means the Russian state is responsible. We will defend these symbols because we reject Russia’s historical falsehoods."
Poland’s foreign ministry said the desecration was reported by members of the local Catholic clergy and Polish community.
It called the act an "outrageous provocation" and demanded that Russia "restore the cemetery to its original condition immediately."
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Source: PAP/X/@sikorskiradek/@PolandMFA
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