Ukraine's army on Wednesday denied Russian claims that it had lost a key bridgehead on the Dnipro river frontline that has faced fierce attacks since Russia lost it.

Russia's defence minister said Tuesday that Moscow's forces had retaken the village of Krynky, seized by Ukrainian troops last year.

Russia has stepped up its offensive ahead of Saturday's second anniversary of its invasion, retaking the symbolic town of Avdiivka last week.

Ukrainian troops have held positions at Krynky since November despite heavy Russian artillery fire.

"We officially inform that this information is not true," the command of the Ukrainian army on the southern front said of the Russian claims over the village.

"The defence forces of southern Ukraine continue to hold their positions (in Krynky)," the command said on social media.

It claimed Russian forces launched an assault on Krynky but suffered "significant losses" and retreated.

AFP was not able to verify the claims.

Russian Defence Minister Sergei Shoigu told President Vladimir Putin on Tuesday that Krynky had been "cleared" of Ukrainian forces.

The US-based Institute for the Study of War said Wednesday that "available open-source visual evidence" as well as reports from both sides "suggests that Ukrainian forces maintain their limited bridgehead in the area."

It added that it had "not observed any visual evidence of recent notable Russian advances" in and around Krynky.

Russian military bloggers also did not report that Krynky was fully under Russian control. One influential channel close to Moscow's forces said Tuesday only that Ukrainian control in the area had "decreased".

Putin handed medals to pilots at a base in the Moscow suburbs after what he called a "turning point" on the front following the fall of Avdiivka.

"Thanks to heroic actions and impeccable preparation, it was possible to achieve a turning point in the most difficult areas of the front," Putin told the pilots, according to Russian news agencies.

Moscow's capture of Avdiivka came after months of battles -- costly for both sides.

In occupied Ukraine, Russian army chief Valery Gerasimov also handed out medals to troops for taking Avdiivka.

"For today the main aim that was given is completed: Avdiivka is liberated," he said, a video posted by the Russian defence ministry showed.

He claimed that Avdiivka was captured in "quite a short time but this was preceded by a long period of preparation."

Russian forces had been trying for months to take Avdiivka.

Ukrainian forces have complained of key artillery and ammunition shortages as they hold off concentrated Russian attacks on the eastern and southern sides of the war frontline. The US Congress has been holding up a huge, crucial aid package.

Russia has suffered important losses, according to Ukraine, but it still has a bigger, better equipped army.

Ukraine's President Volodymyr Zelensky has acknowledged ahead of the anniversary that the country's forces are in "extremely difficult" positions in many places.