A US think tank says Ukrainian troops have advanced deeper into the southern region of Zaporizhzhia as part of their counteroffensive against Russian forces.

The Institute for the Study of War reported on Wednesday that Ukrainian infantry had "infiltrated east of Russian field fortifications near Verbove."

The village of Verbove is about 10 kilometers east of Robotyne, a settlement that Ukraine said on Monday its troops had liberated. The recapture marked progress in the Ukrainian counteroffensive that is believed to be moving more slowly than had been anticipated before its launch in early June.

An article in The Wall Street Journal on Thursday discussed the occupied city of Tokmak, which is located south of Verbove and serves as a logistical hub for Russia.

The article quotes senior Western intelligence officials as saying that recent Ukrainian advances have caused Western intelligence services to be cautiously optimistic that Ukraine can retake Tokmak.

But Ukrainian troops are expected to face fierce resistance as analysts say the Russians have reinforced their defensive lines and apparently deployed elite paratroopers near Robotyne.