After weeks of fighting, Russian troops say they have captured the eastern Ukrainian bastion of Lysychansk and thus taken control of the entire Luhansk region.

According to official sources, Russian Defense Minister Sergei Shoigu informed President Vladimir Putin on Sunday that the entire Luhansk region had been "liberated".

According to the ministry, on Sunday Russian soldiers and pro-Russian separatists first encircled Lysychansk and then entered the city, where they "completely defeated the surrounded enemy".

Initially, no comment was available from the Ukrainian side.

A spokesman for the Ukrainian National Guard said on Saturday evening that the city was heavily fought over, but was still under the control of the Ukrainian army.

A senior representative of the pro-Russian separatists claimed the opposite on Russian television, but added, referring to the city of Lysychansk: "Unfortunately, it is not liberated yet."

The information could not initially be independently verified.

The conquest of Luhansk and, most recently, Lyssychansk in particular, was one of Russia's most important war goals.

The Luhansk and Donetsk Oblasts in Ukraine form the Donbass.

In recent weeks, the Russian offensive has focused primarily on completely dominating the area, parts of which pro-Russian separatists have taken control of since 2014.

After grueling fighting, they recently managed to take the neighboring city of Sieverodonetsk across the river from Lysychansk.

Combat operations were also reported from other parts of the country.

According to the Defense Ministry in Moscow, Russian troops struck military infrastructure in Kharkiv in eastern Ukraine.

In the south, on the outskirts of Mykolaiv, a base used by foreign fighters was hit.

Ukraine, on the other hand, reported that it had destroyed a military base with more than 30 hits from the air in the Russian-held city of Melitopol in the south of the country.

The administrative authority set up by Russia said that while there were no casualties, several private homes near an airfield were hit.