"The Russian FSB [Federal Security Service] resorted to another provocation, announcing the alleged detention of an 'agent of the SBU' in Crimea," it said in a statement.
The statement added that Ukraine believed that such "fake" news was needed by Russia to "intimidate" the peninsula's population, "which is increasingly expressing dissatisfaction with the occupation authorities".
The Russian Federal Security Service (FSB) announced on Tuesday that it detained an Ukrainian security agent who was suspected of staging acts of "sabotage" in Crimea, such as cutting power transmission lines and starting fires in forests.
Ukraine has been wracked by conflict in its eastern regions since March 2014 after Russia’s annexation of Crimea. The fighting with separatists in the Donbass area has led to more than 10,000 deaths, according to the UN.
Along with numerous UN countries, the U.S., the EU, and Turkey also do not recognize Crimea as Russian territory.