Russia is preparing to take what it has described as "appropriate measures" against Poland over a law which could see the demolition of Soviet monuments in the EU country.
Valentina Matvienko, chairwoman of the Council of the Federation, on Wednesday said Russia's foreign ministry would draw up a list of countermeasures.
Matvienko, quoted by Russia's official TASS news agency, said Moscow must respond "adequately".
The Russian reaction came after Polish President Andrzej Duda on Monday signed a bill amending a law on "totalitarian system propaganda".
This law could see Soviet-era monuments torn down.
The Russian Foreign Ministry on Tuesday said Soviet Russia had paid an "immense price" for the WW2 liberation of Poland, losing over 600,000 soldiers and officers.
"Russia has repeatedly drawn Warsaw's attention to the fact that these actions are a direct violation of the international legal obligations in bilateral treaties and agreements that Russia and Poland signed between 1992 and 1994," the ministry said in a statement.
It said: "Needless to say, it will not be left without a response."
