Kiev, Jun 2 (IANS): The situation in Ukraine's eastern Luhansk region "remains difficult because the Russian army is trying to break through our defence line from all directions", regional head Serhiy Haidai has said, media reports said.

Haidai told a Ukraine TV channel on Thursday morning that the main goal of the Russians was the city of Severodonetsk, BBC reported.

"But they had no success there overnight. They are controlling most of the city – but not the whole of the city," as they claimed earlier, added Haidai.

"Fighting continues, and yesterday our boys carried out counter-attacks, pushing back the enemy on some streets and taking several prisoners," he said.

Haidai also said that Russian troops - who are also trying to push on to Severodonetsk's twin city of Lysychansk - are suffering heavy losses to personnel and armoury, but are bringing reinforcements from other battlefields, BBC reported.

He described the territory still under Ukrainian control – believed to be about 5 per cent of the Luhansk region - as a "fortress".

Severodonetsk and Lysychansk - the twin cities on either side of the Siverskyi Donets river - are the easternmost cities still in Ukrainian hands.

Lysychansk is on the right bank of the river, which served as a natural barrier so far, halting the Russian advance.

Russia already controls most of Severodanetsk, where fierce street fighting has been raging for days. Ukrainian officials have not ruled out withdrawing from the city to the more-strategically positioned Lysychansk, BBC reported.

If Russian forces seize the two cities, they would then control all of the eastern Luhansk region.

After a series of military defeats in the first few weeks of the war around the Ukrainian capital Kiev and in the north-east, Russia declared it would focus on capturing Luhansk and the neighbouring Donetsk region - collectively known as Donbas.