MOSCOW (AFP) - Russian security services said Tuesday (Aug 15) they had captured an alleged Ukrainian agent who was planning acts of sabotage including blowing up power lines in Russian-annexed Crimea.

The Federal Security Service (FSB) said in a statement it had detained an "agent of the Ukrainian Security Service... sent to Crimea to carry out acts of sabotage".

It named him as Gennady Lemeshko, describing him as a former military reconnaissance officer in eastern Ukraine and claiming he had been sent to Crimea on a sabotage mission.

He was under orders to put a power line out of order, to light forest fires, set alight an administrative building and cause a landslide to block a highway, the FSB said.

He had been detained on Saturday while "attempting to damage a power line", and was carrying a hand grenade, two sticks of TNT and a hand saw, the FSB added.

Russian state television showed FSB video footage of the man being questioned.

Other footage showed him giving his name as "Gennady Lemeshko" while pinned to the ground near a wooden pole holding up power lines, as a masked agent dumped his possessions out of a bag.

A spokesman for the Ukrainian border service Oleg Slobodyan confirmed that a Ukrainian citizen of that name had entered Crimea on August 9.

"He did not have any banned items with him" and was allowed onto the peninsula by the Russian side, he said.

The Ukrainian military also confirmed Lemeshko had served in the armed forces on a contract from November 2016 to May 2017.

But a Ukrainian Security Service statement described the allegations that one of its agent had been detained as a "provocation" and "fake news".

In 2015, Ukrainian far-right groups and Crimean Tatars opposed to Russia's annexation of their homeland set off a series of explosions that damaged high voltage power lines, cutting power to more than a million residents of the peninsula. Crimea still depends on Ukraine for its electricity.

Moscow annexed the Black Sea peninsula from Ukraine in March 2014 soon after the overthrow of Ukraine's pro-Russian president Viktor Yanukovych following mass protests in Kiev.

Many Western countries imposed sanctions on Russia to punish it for the annexation.