Troop numbers sent into Russia are in thousands, source says; cooling tower at Zaporizhzhia nuclear facility reportedly damaged by fire

Ukrainian sources have indicated that thousands of troops have been committed to its incursion into Russia’s Kursk province, as Moscow and Kyiv traded accusations about a fire at the occupied Zaporizhzhia nuclear power plant 250 miles to the south.

A Ukrainian security official told the Agence France-Presse that the aim of the incursion was to destabilise Russia and string out Russian forces with light, fast-moving attacks. It remains unclear how sustainable the operation will be in the medium term amid Kremlin threats that it will be snuffed out using Russian reserves.

Fighting said to be continuing, with reports of power outages near nuclear power station, despite Moscow’s claim

Russia’s defence ministry claimed it prevented Ukraine from advancing further on the fifth day of the unprecedented attack into the province of Kursk, though there were reports of regional power outages after an electricity substation was hit.

Fighting was said to be taking place in three villages between seven and 11 miles from the international border – Ivashkovskoye, Malaya Loknya and Olgovka – similar locations to where Ukraine is estimated to have advanced previously.