Ukrainian authorities said Tuesday a third bridge to Severodonetsk has been destroyed but that the eastern city is not cut off, despite Russian forces bearing down after weeks of bloody battles.

The head of the city’s administration, Oleksandr Stryuk, said “massive shelling has destroyed a third bridge” over the Siverskyi Donets River, linking the city to Ukrainian-controlled Lysychansk.  

But the city is not isolated,” Stryuk told Ukrainian television.  

“There are communication channels even if they are quite complicated.”

He said Ukrainian troops “continue to defend the city” and that there is round-the-clock fighting, adding that the ground situation “changes every hour”.

On Monday, the Ukrainian army said Moscow’s forces had pushed its troops back from the city centre and Russia-backed separatists alleged the city was “blocked”.  

“The Russian troops do not give up their attempt to storm the city, but the (Kyiv) military holds firm,” Stryuk said.  

He estimated that there are “around 540 to 560” civilians hiding in the shelters of the city’s chemical Azot plant.  

He said it was “difficult” to support them but that there are “some reserves” in the plant.

Regional governor Sergiy Gaiday said Tuesday Russian forces were firing at the plant.

“Russian forces are trying to encircle units of our troops,” Gaiday said, a day after conceding Moscow’s army controlled “more than 70 percent” of the city.

He said Moscow’s forces in the city had been reinforced by “two tactical battalion groups”

President Volodymyr Zelensky said late on Monday that the battle for Severodonetsk was taking a “terrifying” human toll.