(QHA) -

Former Ukrainian Presidents Viktor Yushchenko, Leonid Kuchma and Leonid Kravchuk are concerned about proposals from Russia to hold a referendum on Crimea's accession to Russia, Ukrinform reports.

The ex-presidents said this in a statement, which was posted on the Facebook page of Yushchenko's press secretary, Iryna Vannykova.

"One of the most alarming forecasts for events that started coming true in the last few days is stirring up separatist sentiments in southern and eastern Ukraine... The ideas of representatives of the Russian State Duma to hold a referendum on Crimea's accession to Russia or a relevant request by the Crimean Supreme Council must be condemned as calls for the overthrow of the constitutional system and violation of Ukraine's territorial integrity," the former presidents said.

They also described Ukraine's federalization scenario as dangerous. Thus, according to the former heads of state, law enforcement agencies should investigate the actions of separatists. "Politicians who offer these dangerous recipes... should feel a reaction from the Security Service and the Prosecutor General's Office of Ukraine, which should toughly respond to manifestations of separatism," reads the statement.