Kiev, Jun 26 (IANS) The Mayor of Severodonetsk has confirmed that Russian forces have taken full control of the key Ukrainian city located in the separatist Luhansk region.

"The Russians have fully occupied Severodonetsk, our military has retreated to more prepared positions," the BBC quoted Mayor Oleksandr Stryuk as saying to Ukrainian TV on Saturday.

Capturing Severodonetsk means Russia now controls nearly all of Luhansk region and much of neighbouring Donetsk, the two Russian-backed separatists regions that form the industrial Donbas.

Also confirming the development on Saturday, Head of Luhansk Oblast Military Administration, Serhiy Haidai said 90 per cent of the city has been destroyed.

"Severodonetsk is occupied. After the withdrawal of units of our troops, the enemy has consolidated in the regional centre of Severodonetsk and satellite villages: Syrotyne, Voronove and Borivske.

"The city is 90 per cent destroyed, it will be extremely difficult to survive there, the 'orcs' (Russian soldiers) will not be able to restore communications," he was quoted as saying by Ukrayinska Pravda.

Haidai reiterated that it is now possible to leave the city only through Russian-held territory.

"The Russians are also establishing their own order in the city, They have appointed a commandant and are filming propaganda stories with people emerging from shelters in Azot plant," he further claimed.

Severodonetsk's fall comes days after Ukrainian forces in the city were asked to retreat as "remaining in positions that have been relentlessly shelled for months just doesn't make sense".

Meanwhile, pro-Russian rebels allied with the Russian Army say they have moved into parts of Lysychansk, the city facing Severodonetsk across the Siversky Donets river, the BBC reported.

But Ukrainian officials have not confirmed that.

In his video address late Saturday, President Volodymyr Zelensky pledged to take back "all our cities" occupied by Russia.

But he said the war with Russia had entered an emotionally difficult stage and he did not know how many more blows and losses there would be.