Russia's President Vladimir Putin lays flowers during a ceremony to commemorate the anniversary of the beginning of the Great Patriotic War against Nazi Germany in 1941 near memorials by the Kremlin walls in Moscow, June 22, 2014. (Xinhua/Reuters)

MOSCOW, July 19 (Xinhua) -- Russia is preparing a retaliatory response to Poland's decision to dismantle Soviet monuments, head of the upper house of the Russian parliament said Wednesday.

"(Polish authorities) are violating international agreements with Russia, according to which Poland made a commitment to preserve historic monuments," Russian Federation Council speaker Valentina Matvienko said at a meeting of the council.

The agreements are valid and haven't been terminated by anyone, she added.

Calling the decision "sacrilegious, cynical and absolutely immoral", Matvienko said Moscow is considering a tit-for-tat response.

"A corresponding statement has been made in the Russian Foreign Ministry. I know they are preparing measures appropriate to the current situation," Matvienko was cited by Sputnik news agency as saying.

According to the Russian Foreign Ministry, Polish President Andrzej Duda signed the law of June 22, 2017 on amendments to the law of April 1, 2016, which authorizes the removal of monuments and memorial plaques to the Soviet soldiers who liberated Poland from Nazi occupation in 1944-1945.

Under bilateral agreements reached by the two countries in 1992-1994, Polish authorities are obligated to protect and preserve these memorial facilities including martyr cemeteries and monuments, the ministry said Tuesday in a statement.