Russia accuses Ukraine of trying to get saboteurs into Crimea
The FSB believes Ukrainian special forces had been planning attacks, targeting critical infrastructure.
MOSCOW - Russia said it had thwarted two armed Ukrainian attempts to get saboteurs into Crimea and dismantled a spy network inside the annexed peninsula, accusations Ukraine dismissed on Wednesday as "fake information".
The allegations by Russia's FSB security service follow an uptick in Russian military activity in northern Crimea and heavier fighting in eastern Ukraine, where Ukrainian government troops are battling pro-Russian separatists.
If true, the events - which the FSB said involved at least two armed clashes on the border between Crimea and Ukraine - would be the most serious escalation on the contested peninsula since Moscow annexed it from Ukraine in 2014.
US and European Union sanctions to punish Russia for the land grab remain in place. Moscow has made clear it has no intention of handing the peninsula back to Ukraine and has started to reinforce Crimea militarily.
The FSB said it believed Ukrainian special forces had been planning attacks, targeting critical infrastructure. An FSB employee and a Russian soldier were killed in the clashes at the weekend, it said.
"The aim of this subversive activity and terrorist acts was to destabilse the socio-political situation in the region ahead of preparations and the holding of elections," the FSB said, referring to Russia-wide parliamentary elections next month.
A spokesman for Ukrainian military intelligence denied the accusations. "This is fake information," the spokesman said.
The Ukrainian Defence Ministry said in a statement the FSB's assertions looked like an attempt to justify "acts of aggression" and the redeployment of military units to Crimea.
"Representatives of the Russian special services are trying to divert the attention of the local population and the international community from criminal acts to transform the peninsula into an isolated military base, it said.
The FSB said it had tackled one group of Ukrainian saboteurs in an operation that spanned late Saturday and early Sunday, smashing what it called a Ukrainian spy network.
Ukraine and Russian nationals had been arrested and an arms cache, including 20 homemade explosive devices, ammunition, mines, grenades and specialised weapons commonly used by Ukrainian special forces, had been recovered, it said.
The FSB said the situation escalated further late on Sunday and in the early hours of Monday.
"Ukrainian special forces units tried to break through two more times with groups of saboteur-terrorists but were thwarted by FSB units and other forces," it said.
"The attempts to break through were accompanied by massive covering fire from the neighbouring state and from Ukrainian armoured vehicles."
Security had been beefed up in areas popular with tourists, at key infrastructure and along the Crimea border, the FSB said.