Russia's defence ministry accused Ukraine on Saturday of planning to attack the Kursk nuclear power plant and blamed such a "provocation" on Moscow.
Interfax news agency cited the ministry as saying.
The ministry said Russia would respond harshly in the event of such an attack, which it said would contaminate a large surrounding area.
Ukraine launched an incursion into Russia's western Kursk region on August 6 and has claimed to have taken control of 82 settlements over an area of 1,150 square kilometres (440 square miles) since then.
The Kursk nuclear power plant, however, remains under Russia's control.
US military says it's completed 13th consecutive night of strikes on Iran
India's youth leaders to talk with government but press on with nationwide protests
Spain declares national emergency over wildfires near Madrid and in Avila
Saudi-owned vessel targeted in Red Sea, crew safe, state news agency says
Rubio says US committed to helping end Ukraine war after meeting Lavrov
