Thursday marks six months since Kyiv stormed across the Russian border in a shock ground assault, capturing dozens of Russian border settlements and swathes of territory.

Russia has since been clawing back ground, but Ukraine sees its continued hold on parts of the area as a key bargaining chip in any future peace talks between the two sides.

Russia's defence ministry said Thursday its troops had "foiled an attempted counter-offensive by the Ukrainian armed forces".

It said the new fighting was around the villages of Ulanok and Cherkasskaya Konopelka, southeast of the regional hub of Sudzha, which is under Ukrainian control.

The area is about 10 kilometres (six miles) from the Ukrainian border.

Russia said Ukraine had deployed two mechanised battalions, tanks and armoured vehicles in the attempted attack.

There has been no comment on the fresh offensive from officials in Kyiv.

But Zelensky on Thursday praised his troops fighting in the Kursk region and issued several units with state awards.

"The occupier can and should be beaten on its territory," he said in a social media post.

"The Kursk operation clearly explains the meaning of the principle of 'peace through strength'," he said, referring to a message he has been promoting to secure ongoing military support from Ukraine's western partners.

- 'Exchange fund' -

The Ukrainian military said earlier it had captured 909 Russian soldiers during the six-month offensive there.

"We have significantly replenished our exchange fund -- hundreds and hundreds of Russian soldiers whom we are exchanging to bring Ukrainians back from captivity," Zelensky said in an evening video address.

On Wednesday, each side released 150 captured soldiers in the latest prisoner-of-war exchange.

Russian authorities have faced simmering discontent from Kursk locals, who have seen family members trapped on the opposite side of the front line.

In a meeting with the region's governor on Wednesday, Russian President Vladimir Putin acknowledged the situation there was "very difficult".

Ukraine's shock incursion -- the first onto Russian territory by a foreign army since World War II -- was an embarrassing setback for the Kremlin, almost three years into its full-scale offensive.

The Ukrainian military spokesperson for its forces in Kursk, Oleksiy Dmytrashkivsky, told AFP via phone on Thursday that "a little more than 1,500 people" were still living in part of the region now under its control.

Kyiv says the ground it holds in Kursk will be an important bargaining chip in any future peace negotiations with Russia, whose forces have been making steady gains across the front line in eastern Ukraine.