Ukraine said on Monday it was achieving its goals in its two-week-old incursion into Russia's Kursk region after Moscow confirmed Ukrainian forces had damaged a third bridge after striking two others used to supply troops.

Kyiv says it has seized over 80 settlements in an area of more than 1,150 square km (444 square miles) in Kursk since launching a surprise strike on Aug. 6, the biggest invasion of Russia since World War Two.

President Volodymyr Zelenskiy says the assault on the Kursk region bordering eastern Ukraine is aimed at carving out a buffer zone and wearing down Moscow's war machine, more than two years since Russia's full-scale invasion.

"We are achieving our goals," he wrote on the Telegram messaging app on Monday.

Making clear more Russian soldiers had been taken prisoner, he said: "In the morning, there is another replenishment of the exchange fund for our state."

Kyiv's air force chief said on Sunday that his forces had destroyed two bridges in recent days to weaken enemy logistics.

Russia confirmed on Monday that Ukraine had struck and damaged a third bridge over the Seym River. Ukraine has not yet commented on the third reported strike.

Military analysts have said the structures were part of critical supply lines for Russian troops defending the area. Reuters could not independently confirm the destruction of the bridges or the battlefield situation in Kursk.

In his evening address on Sunday, Zelenskiy said his troops were creating a buffer zone along Ukraine's border with Russia, part of what he described as "maximum counteroffensive actions" aimed at hurting Moscow's military potential.

"Everything that inflicts losses on the Russian army, the Russian state, their military industrial complex and their economy - all this helps us to prevent the widening of the war," Zelenskiy said.

On Monday, Ukraine's ground forces commander, Oleksandr Pavliuk, said on Telegram that troops were "successfully fulfilling tasks" in the Kursk region and capturing Russian prisoners of war to be traded for imprisoned Ukrainian troops.

Pavliuk posted footage of a group of more than 10 people with their hands in the air walking along a road, as well as several more soldiers kneeling beside the road.

He did not say how many Russian prisoners had been taken.

PUSH TOWARDS POKROVSK

Despite gains in Russia's Kursk region, Ukrainian forces were on the defensive near the strategic eastern city of Pokrovsk, where Russia has steadily advanced in recent weeks.

The city, which had a pre-war population of around 60,000, is an important transport hub for Ukrainian supply lines in much of the eastern Donbas region.

Russian troops are now around 10 km from the outskirts of the city, according to Serhiy Dobriak, head of the local military administration.

In comments to Ukrainian media on Monday, he said up to 600 people were leaving on a daily basis, and that municipal services could be cut off within a week as Russian forces close in.