Russia says its troops have taken five villages and the Kharkiv region's governor says they are trying to take more as fierce fighting continues.
But Nazar Voloshyn, a spokesperson for Ukraine's military in the east, insists Moscow's troops are being contained in those villages.
"The enemy is contained in the grey zone, and it is not expanding," he said in a Ukrainian television interview, according to the Kyiv Independent.
The so-called "grey zone" refers to the villages of Borysivka, Ohirtseve, Pylna and Strilecha, all of which are directly on the border with Russia's Belgorod region.
Russian officials said they had also captured another village, Pletenivka.
As we reported earlier, Kharkiv's governor says fighting is ongoing in all the villages Russia has already claimed to have taken.