Russian forces have increased their efforts to advance south of Izium in eastern Ukraine, according to a Thursday morning update by the UK Defense Ministry.
Their intelligence update also states that Russian forces likely want to gain momentum in the area to put further pressure on Sieverodonetsk.
The Ukrainian Defence Ministry said on Thursday that its forces had won back some territory from Russian forces in a counter-offensive in the Kherson area of southern Ukraine.
It gave no details but said the Russian forces had "suffered losses in manpower and equipment," mined territory as they were pushed back and erected barricades for the Ukrainian troops.
Reuters was unable to independently verify the situation on the ground.
Fighting raged on the streets of Sievierodonetsk in eastern Ukraine on Thursday and Russian forces were destroying "everything that can be used for defense," the regional governor said.
Luhansk Gov. Serhiy Gaidai said Russia was shelling areas of the city that are still controlled by Ukraine but that Ukrainian forces would be able to "clean up" in the city once they received long-range artillery.
Ukrainian forces still hold the industrial zone and adjacent areas in the city of Sievierodonetsk, and the situation is "difficult but manageable," Mayor Oleksandr Stryuk said on Thursday.
Defense lines were holding despite intense Russian artillery fire, he said, but that it was now impossible to evacuate people from the city. About 10,000 civilians remained in the city, which is now the main focus of Russia's offensive in Ukraine, the mayor said.
Millions could starve
Millions of people could starve because of Russia's blockade of Ukraine's Black Sea ports, Ukrainian President Volodymyr Zelensky said on Thursday.
Zelensky said in a televised statement that the world was on the brink of a "terrible food crisis," with Ukraine unable to export large amounts of wheat, corn, oil and other products that had played a "stabilizing role in the global market."
"Millions of people could starve because of Russia's blockade of Ukraine's Black Sea ports."Ukrainian President Volodymyr Zelensky
"This means that, unfortunately, there may be a physical shortage of products in dozens of countries around the world," he said. "Millions of people may starve if the Russian blockade of the Black Sea continues."
Russia has seized large parts of Ukraine's coast in nearly 15 weeks of war and its warships control the Black and Azov seas, blocking Ukraine's farm exports and driving up the cost of grain.