Ukrainian authorities have detained two men identified as Russian security agents after they came ashore in a small boat on Ukrainian-government controlled territory along the Black Sea, officials of both countries say.
Ukraine’s border police on June 30 said the two men claimed to be Federal Security Service (FSB) personnel who became lost in the waters of the Black Sea during a training exercise.
Russia's state-run Interfax news agency quoted the FSB as confirming that the men were with the agency. The FSB said the men had taken a "wrong route" during "drills."
The statement also said the FSB hoped the men would be returned to Russia "in the near future."
Ukrainian border guard spokesman Oleh Slobodyan said the men had been jailed for 15 days.
It was not immediately clear where the men washed ashore, but officials said they were detained near the city of Armyansk.
Tensions have been high in Ukraine's occupied Crimea region since Russia illegally annexed the peninsula from Ukraine in 2014.
Russia also has supported pro-Russia separatists in eastern Ukraine, leading to a prolonged conflict that has left more than 10,000 people dead.
Western nations have imposed sanctions on Moscow in response to its interference in Ukraine.