Ukraine says it has been reinforcing its power generation capacity in time for the arrival of winter. It is feared that Russian forces may renew attacks on the Ukrainian energy grid in the coming months.

Ukraine's Energy Ministry said on Saturday that it had been modernizing thermal power units and restoring electric facilities damaged by Russian strikes.

Ukrainian President Volodymyr Zelenskyy said on Friday that what he called "Russian terrorists" would once again try to destroy his country's energy system this winter.

He also warned that Russian forces would try to launch more attacks on Ukrainian energy facilities than in the previous winter.

Ukraine experienced serious shortages of electricity last winter after Russian forces started to unleash waves of attacks on power plants, substations and other energy installations from October last year.

Meanwhile, an assessment of fighting in Ukraine released by a US think tank on Saturday suggests both Ukrainian and Russian forces have made gains on frontlines.

The Institute for the Study of War cited a Ukrainian military spokesperson as saying that Ukrainian forces had advanced up to 300 meters in different directions near Bakhmut over the past day. Bakhmut is a battleground city in the eastern region of Donetsk.

The institute also quoted Ukrainian military sources as stating that Ukrainian forces advanced in two areas in the southern region of Zaporizhzhia.

But it added that Russian forces continued offensive operations in the eastern region of Luhansk on Saturday and reportedly advanced.