Ukrainian forces have halted Russia's recent advance into the northern Sumy region and have stabilised the front line near the border with Russia, Ukraine's top military commander said overnight.

Colonel General Oleksandr Syrskyi, commander in chief of Ukraine's armed forces, said that Ukrainian successes in Sumy had prevented Russia from deploying about 50,000 Russian troops, including elite airborne and marine brigades, to other areas of the front line.

His claim could not be independently verified, and Russian officials made no immediate comment.

Russian forces have been slowly grinding forward at some points on the roughly 1000km front line, though their incremental gains have been costly in terms of troop casualties and damaged armour. The outnumbered Ukrainian army has relied heavily on drones to keep the Russians back.

Months of US-led international efforts to stop the more than three years of war have failed. Amid the hostilities, the two sides have continued swaps of prisoners of war agreed on during recent talks between their delegations in Istanbul.

Russia's Defence Ministry and Ukrainian authorities said another exchange took place on Thursday.

Ukraine's co-ordination headquarters for POWs said the swap included injured soldiers and those with health complaints. The youngest was 24 and the oldest was 62, it said, adding that more exchanges were expected soon.

Sumy, the city which is the capital of the Ukrainian region of the same name, had a prewar population of about 250,000. It lies about 20km from the front line. Russia's push into the region earlier this year compelled Ukraine to strengthen its defences there.

A special defence group has been formed to improve security in Sumy and surrounding communities, Syrskyi said, with a focus on improving fortifications and accelerating construction of defensive barriers.

In March, Ukrainian forces withdrew from much of Russia's neighbouring Kursk region, parts of which they had controlled after a surprise cross-border attack in August.

That retreat enabled Russia to launch a counteroffensive that advanced between 2km to 12km into Ukrainian territory, according to different estimates.

Ukrainian officials say fierce fighting is also taking place in the eastern Donetsk region.

The Russian Defence Ministry said on Thursday that its forces had captured two villages, Novoserhiivka and Shevchenko, in Donetsk.

Capturing Shevchenko marked an important stage in Russia's ongoing offensive that is trying to break into Ukraine's Dnipropetrovsk region, which borders Donetsk and is a major industrial centre, according to the ministry.

Meanwhile, the two sides continued to launch long-range strikes.

The Russian ministry said 50 Ukrainian drones were downed over nine regions overnight, including three over the Moscow region.

Ukraine's air force said that Russia deployed 41 Shahed and decoy drones across the country overnight, wounding five people. It said that 24 drones were either intercepted or jammed.

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