Ukraine is conducting a manoeuvre in some areas of the embattled town of Avdiivka to withdraw troops to "more advantageous positions" and in other places is trying to push out Russian troops, military spokesman Dmytro Lykhoviy said on Thursday.

He said in televised comments that Ukraine had activated a backup logistics route into the town, but that supplies into Avdiivka and evacuations from it were "difficult".

Russia is trying to capture the eastern town after months of heavy fighting in the war.

"In Avdiivka a manoeuvre is underway in some places to withdraw our units to more advantageous positions, in some places to force (the Russians) out of positions," Lykhoviy said.

"Therefore the key announcement with regards to all this is that supplies to Avdiivka and evacuations from there are difficult," he said, adding that they had set in action a "reserve logistics artery" that had been prepared in advance. (Reporting by Yuliia Dysa; writing by Tom Balmforth; editing by Mark Heinrich and Sharon Singleton)