Ukraine is justified in using severe methods to fight separatism, Ukrainian President Petro Poroshenko has said.

"Severe methods [to fight separatism] are completely justified to avoid paying the high price the Ukrainian people do now," Poroshenko said during events commemorating the 23rd anniversary of the establishment of the Security Service of Ukraine in Kyiv on Wednesday.

Poroshenko added that separatism needs to be "nipped in the bud."