Two Russian guards have been detained in Ukraine after crossing the border near the Black Sea peninsula of Crimea, TASS news agency cited Russia's Federal Security Service (FSB) as saying on Friday.

The FSB said the guards were detained by Ukrainian authorities on Thursday night after "straying from the path" and entering Ukrainian territory near the town of Armyansk.

Russia annexed Crimea from Ukraine in 2014.

"We hope that in accordance with the norms of international law, the employees ... will soon be returned to the territory of the Russian Federation," TASS quoted the FSB's press service as saying.