The spokesperson for the Russian Defense Ministry confirmed that Russian forces have repelled two attacks by Ukrainian sabotage and assault groups.

"The [Russian] units … repelled two attacks by enemy sabotage and assault groups in the Aleksandro-Artemovsk and Avdeevsk directions," the spokesperson told Sputnik.

According to the news agency, Russian forces have targeted a site for the temporary deployment of Ukrainian soldiers and ammunition depots.

It added that Russian TOS-1A "Solntsepek" (Blazing Sun) thermobaric rocket launchers have imposed manpower damage in the Orikhovo-Vasylivka area.

Read more: Drone attack damages Russian oil pipeline building in Pskov

Air raid sirens sound across most of Ukraine

In a related context, Ukrainian media reported that several explosions were heard overnight in the Ukrainian cities of Kiev, Poltava, Khmelnytskyi, and Lvov.

According to air raid data from Ukraine's Ministry of Digital Transformation, air raid sirens sounded across most of the country in the early hours of Monday. 

The TSN TV channel mentioned that explosions were heard in Kiev, Poltava, Khmelnytskyi, Lvov, Odesa, Vinnytsia, and Cherkasy.

Shortly after midnight, air raid warnings sounded in Mykolaiv, Kirovohrad, Chernihiv, Sumy, and Kiev, as well as Ukraine-controlled parts of the Kherson Region.

Later in the night, warnings were issued in Zhytomyr, Kharkov, and Odessa, as well as in the Rivne, Khmelnytskyi, and Vinnytsia regions.

Read more: Russian FSB thwarts Ukrainian attack on nuclear power plants