Russian forces now control "part" of Severodonetsk, a city in eastern Ukraine that they have been shelling and trying to take for weeks, the governor of the region announced on Tuesday.

“The situation is ultra-complicated. Part of Severodonetsk is controlled by the Russians,” Sergei Gaïdaï, head of the Lugansk region, said on Telegram.

He said, however, that the Russians "cannot advance freely", with Ukrainian fighters "still remaining" in the city.

"The enemy is planning an operation to clear the territory of the neighboring villages," said Mr. Gaïdaï, saying that he had no news of three doctors who had disappeared since the day before.

On Monday, the governor announced that Russian forces had advanced to the center of Severodonetsk, a city of some 100,000 inhabitants before the war today largely destroyed and deserted.

The city has been shelled for weeks by Russian forces and the pro-Russian separatists fighting alongside them. Dozens of civilians were killed there.

Severodonetsk and its twin city of Lysychank are located more than 80 km east of Kramatorsk, which has become the administrative center of Ukraine's Donbass since Moscow-backed separatists seized the eastern part of this large coalfield in 2014.