The Russian Defense Ministry said on March 6 that Russian forces had captured the village of Basivka, right across the border with Russia's Sudzha, and attacked Ukrainian forces at 12 other points in Sumy province.
The Russian Defense Ministry also said that Russia is defeating Ukrainian units in Russia's Gornal, Guevo and Oleshnya settlements.
However, Ukrainian officials denied the information, saying Russian forces could not control Basivka.
"Up to today, the Russian army has not been able to control Basivka in Sumy province. They are trying to penetrate into attack groups and search for safe havens to gain ground, but the opponent is being destroyed," Andriy Kovalenko, an official with the National Security and Defense Council of Ukraine, said on the Telegram messaging app on April 6.
He added: "Combat in the Sumy border area is very complicated and occurs daily at some points and is also taking place in the Kursk border area."
The DeepState map of pro-Ukraine ground fighting shows that Ukraine is controlling about 63 square kilometres of Russian territory, down from the 1,400 square kilometres that Kiev declared last year.
About 81 square kilometres of other territory along the border - including Basivka - are classified by DeepState as "undeterred" control areas.
Kiev deployed thousands of soldiers across the border into Russia's Kursk region in August last year, but Russian attacks in recent months have pushed most of Ukraine's forces out of Kursk.
Russian President Vladimir Putin has repeatedly suggested that Russian forces set up a buffer zone along the border.
Russia now controls nearly a fifth of Ukraine's territory, including Crimea, which it annexed in 2014 and most of the four other regions that Russia declared to be annexed after the conflict broke out in 2022.
According to Russia's estimates, Russia controls the entire Crimea, most of Lugansk and more than 70% of the Donetsk, Zaporizhzhia and Kherson provinces. Russia also controls a small part of Kharkiv province.
