Russia's defense ministry said its troops repelled Ukrainian forces who on Thursday mounted a counteroffensive in Russia's western Kursk region.

The Russian report came six months to the day that Ukraine's military pushed across the border into the Kursk region, the biggest foreign attack on Russia since World War II.

Russian forces have since fought back against the Ukrainian incursion, regaining much lost ground in the region.

Russia's defense ministry said Ukrainian troops and armoured vehicles launched eight waves of attacks near the villages of Ulanok and Cherkasskaya Konopelka.

"As of 2100 (Moscow time), units of the North group of forces have thwarted an attempted counterattack by the Ukrainian armed forces aimed at the settlements of Cherkasskaya Konopelka and Ulanok," the ministry said on Telegram.

The settlements were under Russian control, the ministry said. Ukrainian forces suffered heavy losses, including more than 200 servicemen and dozens of vehicles, it said.

Reuters could not independently confirm the battlefield reports.

The Ukrainian military made no official statement. But unofficial Ukrainian military blogs said Kyiv's military made some limited gains in tactical positions and discounted Moscow's reports of heavy losses.

Ukrainian President Volodymyr Zelenskyy acknowledged the six-month anniversary of the incursion but made no mention of a counteroffensive.

Speaking in his nightly video address, Zelenskyy said the incursion "brought the war home for Russians so that they might feel just what war is. And they are feeling it."

Ukraine's foothold in Kursk has shrunk significantly since the Aug. 6 incursion but could be a useful bargaining chip in potential peace talks.

Russia controls about a fifth of Ukraine as the war approaches its three-year anniversary on February 24.