Analysts say Russia may be preparing for urban combat to defend the city of Kherson, as Ukraine steps up its counteroffensive to recapture the southern region of Kherson, annexed by Russia.

Civilian casualties continue to rise in Ukraine. The governor of Donetsk said on Tuesday that Russian attacks killed seven people and wounded three others in the Ukrainian stronghold of Bakhmut.

The Institute for the Study of War, a US think-tank, pointed out in its assessment on Monday that Russian forces are likely preparing the city of Kherson for urban combat.

Ukrainian political analyst Taras Berezovets, who's been engaged in battles as a member of the military, told NHK that Russia is deploying airborne forces and newly mobilized reservists, along with tanks and ammunition, to the right bank of the Dnipro River, where Kherson city is located. He added that combat is expected to continue for weeks.

Russia's defense minister Sergei Shoigu and Chief of General Staff Valery Gerasimov have raised concerns over unverified claims that Ukraine may use a "dirty bomb" in their recent telephone talks with officials from other countries. A dirty bomb is a conventional explosive that scatters radioactive material.

Ukraine has criticized the claim, saying the information was fabricated. The United States and NATO have also called the claim "false allegations."

The Institute for the Study of War says the Kremlin is intensifying its information operation, pointing out that Russia may be trying to hamper Western nations' support for Ukraine.