Russia's main intelligence agency says it has detained a Ukrainian intelligence agent who was plotting acts of sabotage in the Russia-occupied Crimea.

Russia annexed Ukraine's Crimean peninsula in 2014 after a hastily called referendum.

The FSB in a statement on Tuesday said the Ukrainian intelligence officer arrived in Crimea earlier this month and was planning to damage power lines on the peninsula's southern coast, which would leave tens of thousands without electricity, as well as set fire to the forest and blockade the road. The FSB said the agent, whom it identified as Gennady Limeshko, was caught red-handed on Saturday as he tried to cut a power line.

The Ukrainian intelligence agency SBU was not immediately available for comment.