(Reuters) - Russia's defence ministry said on Tuesday its troops had inflicted heavy strikes on Ukrainian units in Russia's western Kursk region, where Ukraine's military reported an escalation in fighting in the previous 24 hours.

Ukraine, which seized part of the Kursk region in early August and has held on to it for five months, launched a new offensive there on Sunday but has not provided details of the operation or stated what the objectives are.

Ukraine's general staff on Tuesday reported 94 clashes in Kursk region for the past day, compared with 47 the day before.

The U.S.-based Institute for the Study of War said geolocated footage published on Sunday and Monday indicated recent Ukrainian advances in three areas northeast of the town of Sudzha.

It said Russian forces were trying to attack elsewhere in the region. Russian military bloggers reported fighting in Malaya Loknya, northwest of Sudzha.

A Russian defence ministry statement listed six locations where it said its forces had defeated Ukrainian brigades, and seven more - including one on the Ukrainian side of the border - where it said it had carried out strikes on Ukrainian troops and equipment.

Reuters could not independently verify battlefield reports from either side.

Capturing and retaining a slice of Russian territory in the Kursk region has given Ukraine a bargaining chip in potential peace talks, as both sides fight to improve their battlefield positions before Donald Trump's return to the White House.

The U.S. president-elect, who will be sworn in on Jan. 20 - has repeatedly said he will end the nearly three-year-old war quickly, but without saying how.

Ukraine's offensive in Kursk since last August has come at a cost, however, as Russia has advanced in eastern Ukraine at the swiftest pace since 2022. Russia controls about a fifth of its neighbour's territory.

Western and Ukrainian assessments say about 11,000 troops from Russia's ally North Korea are fighting with Moscow's forces in Kursk. Russia has neither confirmed nor denied their presence. Ukraine and the United States say large numbers have been killed, with U.S. Secretary Antony Blinken giving a figure on Monday of more than 1,000 North Koreans dead or wounded.

Ukraine's special forces said on Tuesday they had killed 13 North Korean soldiers, and posted photos on Telegram which they said showed their bodies and ID documents.

(Reporting by Mark Trevelyan and Alexander Marrow in London and Anastasiia Malenko in Kyiv, Editing by Timothy Heritage)