Kyiv, Ukraine - Ukrainian President Volodymyr Zelensky said Saturday his forces were "strengthening" their positions in Russia's Kursk region, where Kyiv has been mounting a major ground offensive for more than 11 days.

His comments came a day after Moscow accused Ukraine of destroying a key bridge over a river in the border region, as Kyiv seeks to disrupt supply routes and the movement of Moscow's troops in the area.

Ukrainian army chief Oleksandr Syrsky "reported on the strengthening of the positions of our forces in the Kursk region and the expansion of stabilized territory," Zelensky said in a post on Telegram.

"As of this morning, we have replenished the exchange fund for our country," Zelensky said, referring to Russian soldiers Ukraine has captured to be used in future prisoner swaps.

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"I thank all the soldiers and commanders who are taking Russian soldiers prisoner and thus bringing the release of our soldiers and civilians held by Russia closer," Zelensky said.

Kyiv claims to have taken control of more than 80 settlements in the lightning incursion, which caught the Kremlin off guard almost two and a half years into its full-scale invasion of Ukraine.

The Russian defense ministry said on Saturday it had pushed back Ukrainian forces near three settlements in the Kursk region and was searching for "mobile enemy groups" trying to pierce deeper into the country.

Russian officials on Friday accused Ukraine of striking a strategically important bridge just a couple dozen miles away from fighting in the Kursk region.

The region's governor, Alexei Smirnov, said on Friday evening the bridge was in the Glushkovsky district, some seven miles away from the border.

An aerial video published by Ukrainian air force commander Mykola Oleshchuk appeared to show the bridge being hit by a projectile at high speed before collapsing into a cloud of smoke.

"Ukrainian pilots are conducting precision strikes on enemy strongholds, equipment concentrations, as well as on enemy logistics centers and supply routes," he said on Telegram.

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Russian foreign ministry spokeswoman Maria Zakharova said the bridge was "completely destroyed" and that "volunteers providing assistance to the evacuated civilian population were killed."

"All those responsible for these inhumane acts will be severely punished," she said.

Russia separately accused Ukraine on Saturday of dropping an explosive charge on a road near the occupied Zaporizhzhia nuclear power plant in southern Ukraine.

The plant, which was seized by Russia's forces early in the war, has come under repeated attacks that both sides have accused each other of carrying out.

Russia meanwhile attacked at least four Ukrainian regions on Saturday, according to officials, including the northeastern region of Kharkiv, where prosecutors said shelling killed a 49-year-old woman.

While the incursion has delivered a major morale boost to Kyiv, it appears to have had little impact on the larger battles raging in Russian-occupied parts of eastern Ukraine.

Zelensky said on Saturday there had been "dozens of Russian assaults" on Ukrainian positions near the towns of Pokrovsk and Toretsk, where Moscow has made a string of advances in recent weeks.

"Our soldiers and units are doing everything to destroy the occupier and repel the attacks," Zelensky said, stressing the situation was "under control."

Russia said Friday its forces had captured another village near Pokrovsk, a Ukrainian-held logistics hub that lies on a road supplying troops and towns across the eastern front.

Russian forces have been inching towards the town for months, taking a string of tiny villages over the past weeks.

The head of Pokrovsk's military administration, Sergiy Dobryak, warned on Thursday that Russia was a little over six miles from the outskirts of the city and urged remaining residents to evacuate.