Ukraine President Volodymyr Zelensky has written on social media that the southern city of Kherson was "ours" after Russia announced it had completed a retreat from the regional hub.

"Our people. Ours. Kherson," Mr Zelensky wrote on Telegram, alongside a Ukrainian flag emoji and amateur video footage that appeared to show Ukrainian troops gathering with residents of the city.

Authorities in Kyiv earlier said its forces are entering the southern city of Kherson and hailed an "important victory" after Russia announced its troops had retreated from the only regional capital it has captured after nearly nine months fighting.

The announcement that Moscow's pullout was over came hours after Russian strikes killed seven people in Mykolaiv, a city near Kherson, that Russian troops have battered for months.

"Kherson is returning to Ukrainian control and units of the Armed Forces of Ukraine are entering the city," the defence ministry said on social media.

It added that its artillery teams had clear views over Russia's routes to retreat and warned: "Any attempts to oppose the Armed Forces of Ukraine will be stopped."

Russia announced earlier that it had finished pulling back its troops.

'No regrets'

"Ukraine is gaining another important victory right now and proves that whatever Russia says or does, Ukraine will win," Foreign Minister Dmytro Kuleba wrote on social media.

He posted an amateur video showing Ukrainians removing a billboard near Kherson that proclaimed: 'Russia is here forever'.

The Ukrainian flag in front of a damaged settlement in Potemkin village which is recently retaken from Russian Forces in Kherson

Ukrainian soldiers inspect a destroyed Russian tank at an undisclosed location, eastern Ukraine

Ukraine's parliament published pictures of people with Ukrainian flags in the city centre.

Kherson was the first major urban hub to fall to Russian troops after President Vladimir Putin announced Moscow's "special military operation" in Ukraine, and it was the only regional capital his forces seized.

Its full recapture by Kyiv would be a political and symbolic blow to Mr Putin and open a gateway for Ukraine's forces to the entire Kherson region, with access to both the Black Sea in the west and Sea of Azov in the east.

It would also disrupt an important land bridge for Russia between its mainland and the Crimean peninsula, which Moscow annexed from Ukraine in 2014.

Ukrainian officials were initially wary after Moscow announced this week that it would pull forces to defensive positions on the east bank of the river in Kherson.

While it would appear a major Russian setback in a region, Mr Putin claimed to have annexed, the Kremlin today dismissed any suggestion the status of the region had changed after the retreat.

Ukrainian servicemen repair a damaged tank as they move toward Kherson

"This is a subject of the Russian Federation. There are no changes in this and there cannot be changes," Kremlin spokesman Dmitry Peskov told reporters.

The region of Kherson was one of four territories of Ukraine that Putin claimed to have annexed during a grand ceremony in the Kremlin in late September, vowing at the time to use all available methods to defend it from Kyiv.

'Cynical' attack

Asked by reporters whether Russia now regretted annexing Kherson, Mr Peskov said the Kremlin had "no regrets" about the move.

The announcement from Moscow that it had finished retreating in Kherson came after a fatal Russian strike on a residential building in the southern city of Mykolaiv.

Russian troops failed to capture the Black Sea city from Ukraine in the early stages of their invasion but have launched rockets and missiles on the embattled city for months.

Employees work on damaged equipment at a power substation after a missile attack in central Ukraine

An AFP journalist at the scene of the strike saw a gaping hole cut through a Soviet-style residential building with emergency workers in yellow helmets on the site clearing rubble.

Mykolaiv regional governor Vitaliy Kim said on social media the toll had risen to six.

Ukrainian President Volodymyr Zelensky branded the strike a "cynical response to our successes at the front".

He announced late last night that his forces had recaptured more than 40 towns and villages in southern Ukraine during a counter-offensi ve begun in August.

The United States also yesterday announced a new $400-million security assistance package for Kyiv, including defence systems and surface-to-air missiles.

"(With) Russia's unrelenting and brutal air attacks on Ukrainian civilian and critical infrastructure, additional air defence capabilities are critical," Deputy Pentagon Press Secretary Sabrina Singh told journalists.

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