"An annexation means breaching international agreements and it is doubtless that agreements guaranteeing Ukraine's territorial integrity were breached," Zeman said in a response to a reader's question published by, NYT reported.

"On the other hand, I agree with you that (Soviet leader Nikita) Khrushchev made an unforgivable silly thing and world's politicians acknowledge today that Crimea cannot be given back to Ukraine," Zeman said. He did not specify who those politicians were.

Read alsoCzech PM: No diplomacy with self-proclaimed Donbas republicsKhrushchev gave Crimea to Ukraine, then part of the Soviet Union, in 1954.

The Czech government, which has the main say in the foreign policy of the EU country, has followed the common stance of the bloc regarding the sanctions on Russia.

Read alsoRussian defense minister arrives in Crimea for key stage of Caucasus-2016 drillsZeman has spoken out against the EU sanctions and has regularly expressed pro-Russian views. He was the only Western leader to attend the May 2015 celebrations in Moscow to mark the end of World War Two.

Read alsoMan severely beaten wearing Ukrainian symbols in occupied Crimea (photo, video)The Czech president earlier said he did not rule out his visit to Moscow as early as this year or in 2017.