Ukrainian President Volodymyr Zelensky has walked the streets of the newly liberated city of Kherson, hailing Russia’s withdrawal as the “beginning of the end of the war”.

But he also acknowledged the heavy price Ukrainian troops are paying in their grinding effort to push back the invaders.

The retaking of Kherson was one of Ukraine’s biggest successes in the nearly nine-month-old war which could serve as a springboard for more advances against Russia.

President Joe Biden called it a “significant victory” for Ukraine.

“I can do nothing but applaud the courage, determination and capacity of the Ukrainian people, the Ukrainian military,” he said on the sidelines of a Group of 20 summit in Indonesia.

Large parts of eastern and southern Ukraine are still under Russian control, and the city of Kherson itself remains within reach of Moscow’s shells and missiles. Heavy fighting continued elsewhere in the country on Monday.

In Kherson, Mr Zelensky awarded medals to soldiers and posed with them for selfies while striking a defiant note.

“This is the beginning of the end of the war,” he said. “We are step by step coming to all the temporarily occupied territories.”

Volodymyr Zelensky posed for selfies but also had a grim warning. Photo: AAP

But he also grimly noted that the fighting “took the best heroes of our country.”

The end of Russia’s occupation of the city has sparked days of celebration. But with winter approaching, its residents are without heat, water and electricity, and short on food and medicine.

NATO Secretary-General Jens Stoltenberg, while visiting The Hague, warned that “we should not make the mistake of underestimating Russia.”

“The Russian armed forces retain significant capability as well as a large number of troops, and Russia has demonstrated their willingness to bear significant losses,” he said.

Kremlin spokesman Dmitry Peskov refused to comment on Mr Zelensky’s visit, saying only that “you know that it is the territory of the Russian Federation.” Russia illegally annexed the Kherson region and three other provinces earlier this year.

Residents said Russian troops plundered the city as they departed last week. They also wrecked key infrastructure before retreating across the wide Dnieper River to its east bank.

Putin’s attack dog ‘hospitalised’

Russian Foreign Minister Sergey Lavrov was reportedly treated for a heart condition after being taken to hospital in Bali ahead of the G20 summit.

Indonesian authorities confirmed Vladimir Putin’s mouthpiece visited and later left a Bali hospital.

But Russia denied he had been hospitalised, calling it “the highest level of fakes.”

Russia’s top diplomat arrived on the resort island the Sunday evening to take part in the meeting of the world’s leading economies, which begins on Tuesday.

Mr Lavrov is the highest-ranking Russian official at the G20 meeting, which US President Joe Biden, China’s Xi Jinping and other leaders are attending.

Bali Governor I Wayan Koster said Mr Lavrov was taken to Sanglah Hospital, the island’s biggest, “for a health checkup.”

“He left the hospital after a brief checkup and his health is in good condition,” the governor said on Monday.

Four Indonesian government and medical officials earlier told The Associated Press that Mr Lavrov was treated at the hospital in the provincial capital, Denpasar.

All of those officials declined to be identified as they were not authorised to discuss the matter publicly.

Two of the people said Mr Lavrov had sought treatment for a heart condition, with one later saying he’d returned to his hotel.

The hospital did not immediately comment.

Russian Foreign Ministry spokesperson Maria Zakharova posted a video of Mr Lavrov, looking healthy in a T-shirt and shorts, in which he was asked to comment on the report.

“They’ve been writing about our president for 10 years that he’s fallen ill. It’s a game that is not new in politics,” Mr Lavrov says in the video.

Tweet from @nexta_tv

Russia’s state news agency Tass separately cited Mr Lavrov as saying, “I’m in the hotel, reading materials for the summit tomorrow.”

Asked about Mr Lavrov’s situation, UN Secretary General Antonio Guterres said he “did not know about what happened to Minister Lavrov.

“I wish him the best possible recovery and hope that tomorrow it will be possible to meet.”