Russian President Vladimir Putin has held a meeting of the country's top brass to discuss boosting security in Crimea following the reports of foiled terrorist attacks.

The Russian intelligence said Wednesday that two people were killed while fending off what it described as a series of attempted attacks in Crimea by Ukrainian "saboteurs." Ukraine rejected the claims as "fantasy" and "a provocation."

Russia annexed the Black Sea peninsula in March 2014 following a hastily called referendum, an event that sparked Russia-backed separatists to begin fighting in eastern Ukraine, where deadly fighting is still ongoing.

The Kremlin on Thursday said Putin chaired a Security Council session to discuss "additional measures" to ensure security at Crimea's de-facto border, the territorial waters around it and the Crimean airspace.