The Atesh partisan group sabotaged a key railway connection between Russia's Rostov-on-Don and the occupied Ukrainian city of Mariupol used by the Russian military, the group claimed on July 9.
An Atesh operative burned a relay cabinet near the Russian city of Shakhty, the partisans said, publishing purported footage of the sabotage without specifying the date. The Kyiv Independent could not verify the claims.
Russia began constructing new railway connections to link Russia with Crimea and other occupied territories in southeast Ukraine.
This is designed to reduce the Russian military's dependence on the Kerch Bridge and ferry crossing – linking eastern Crimea to Russia's Krasnodar Krai – which have proved vulnerable to Ukrainian attacks.
Petro Andriushchenko, an advisor to the exiled mayor of Mariupol, said in mid-June that the railway line between Rostov-on-Don and the occupied Ukrainian city was almost finished.
"This is one of the main railways in the region, connecting Russia to Ukraine's Donetsk Oblast. It is actively used to transport military equipment and personnel to the front," Atesh said on Telegram.
"We continue to fight the occupiers with all our might, and the number of our sabotages will increase every day."
The Atesh movement claims to be active in both occupied areas of Ukraine and inside Russia itself.
Over the weekend, Atesh partisans claimed that they had successfully sabotaged a railway line near the Russian city of Yekaterinburg, halting trains being used to transport North Korean ammunition.
The group also claimed to have successfully infiltrated a Russian air base in Voronezh in June.