Moscow, Russia - Russia's FSB security service said Thursday it launched criminal cases against journalists, including a CNN correspondent, who reported from Ukrainian-held parts of Russia's Kursk region for "illegally" crossing the border.

The FSB said it had opened cases over the illegal crossing of the state border – punishable by up to five years in prison – against a CNN journalist and two Ukrainian journalists.

"They will shortly be placed on an international wanted list," it said.

It said the journalists had filmed video footage in the area of Sudzha, a town captured and now controlled by advancing Ukrainian troops.

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The FSB named the CNN reporter as Nick Paton Walsh, the channel's chief international security correspondent, who reported from Sudzha for the channel on August 16.

Paton Walsh is a British journalist who previously reported for Channel 4 News and The Guardian newspaper in Moscow.

The FSB named the Ukrainian journalists as Diana Butsko, who reported from Sudzha for Hromadske news site and Olesya Borovik, who reported from there for My-Ukraina television.

The FSB said the criminal case against the journalists was on the same charge as it earlier launched over two Italian journalists from RAI public broadcaster, Simone Traini and Stefania Battistini, who reported from Sudzha last week.

Russia last week summoned the Italian ambassador over their coverage and opened a criminal probe against the Italians on Saturday.