Russia's domestic security agency says it has arrested a retired navy officer in Crimea accused of spying for Ukraine.

The Federal Security Service said Thursday that Leonid Parkhomenko was gathering information on Russia's Black Sea Fleet for the Ukrainian military intelligence. It said he was arrested Tuesday on treason charges.

Ukrainian officials dismissed the claim as a provocation

Relations between the ex-Soviet neighbors have been at freezing point following Russia's annexation of Ukraine's Crimean Peninsula and support for a pro-Russia insurgency in eastern Ukraine.

Last week, Russian officials announced the arrest of several Ukrainians accused of plotting acts of sabotage in Crimea. Ukraine over the weekend arrested two Russian servicemen from Crimea, who had previously served in the Ukrainian military, accusing them of treason.