Russia says its air defense systems shot down what it calls Ukrainian drones targeting Moscow early on Tuesday.

The defense ministry said the drones flew over the suburbs of the capital, as well as the Kaluga and Tver regions surrounding the Moscow region.

Moscow Mayor Sergei Sobyanin posted on social media that air defense destroyed the drones and falling debris damaged a facility in the western district near Moscow.

On Monday, President Vladimir Putin said at a news conference that the Ukrainian counteroffensive had "failed, not stalled."

Defence Minister Sergei Shoigu also told reporters that Ukraine's losses were grave, saying that Russian forces destroyed six Ukrainian tanks on Sunday alone.

US think tank The Institute for the Study of War said on Monday that Ukrainian light infantry has advanced to positions beyond the anti-tank ditches and obstacles in the southern region of Zaporizhzhia.

Ukraine maintains that its forces have breached Russia's first defense line. They are aiming to advance to the key hub of Tokmak in the south, while Russia's military has also reportedly deployed new troops in the area.