Volodymyr Zelensky has posted a video of himself visiting an island that became a symbol of Ukrainian resistance - as the war enters its 500th day.

At the start of the war, Ukrainian soldiers defending Snake Island famously defied an order from a Russian warship to surrender.

The Black Sea island was seized by Russia, but later reclaimed by Ukraine.

In a video, the Ukrainian president called it a "place of victory" that would never be reconquered.

In the undated clip, posted on Telegram, Mr Zelensky described it as proof that Ukraine would return every inch of its territory taken by Russia since the war began on 24 February 2022.

"I want to thank from here, from this place of victory, each of our soldiers for these 500 days," Mr Zelensky said in the video, in which he was shown arriving on the island by boat and leaving flowers at a memorial.

The Ukrainian president later announced the return home of five former prisoners of war captured by the Russians during last year's siege of the Azovstal steel plant in Mariupol.

They had been in Turkey since September 2022 after being freed from Russian captivity as part of a wider prisoner exchange.

Russia's flagship Moskva sailed to Snake Island within hours of the start of the war and ordered Ukrainian soldiers on the island to give themselves up.

"I suggest you lay down your weapons and surrender to avoid bloodshed and needless casualties. Otherwise, you will be bombed," said a Russian officer.

The Ukrainian response and verbal exchange went viral as a soldier replied telling the Russian warship to "go to hell" - although in far cruder language.

Snake Island was seized and the Ukrainian soldiers were taken prisoner - but later exchanged for Russian captives.

Ukrainian forces recaptured the island in June last year.

The deputy head of the UN's human rights monitoring team in Ukraine, Noel Calhoun, said the 500th day was "another grim milestone in the war that continues to exact a horrific toll on Ukraine's civilians".

The UN estimates more than 9,000 civilians, including some 500 children, have been killed since the war began, although it said the real number could be much higher.

Mr Zelensky made his video address after spending much of the week visiting European leaders, as part of a diplomatic tour to ramp up support for Ukraine's bid to join Nato.

He also welcomed the news that the US would be supplying Ukraine with cluster bombs - a weapon that has been banned in more than 120 countries because they have a record of killing civilians.

Both Ukraine and Russia have been using cluster munitions throughout the war, but the US's decision has proved controversial.

Mr Zelensky called the latest US arms package "timely, broad and much-needed", tweeting that it "will provide new tools for the de-occupation of our land".

Ukraine's long-awaited counter-offensive to retake territory from Russia's occupying forces began last month - although Mr Zelensky has admitted progress has been slow.

The effort has been focused in the eastern Donetsk and south-eastern Zaporizhzhia regions of the country, while there have also been slow advances in the city of Bakhmut.

Russia, meanwhile, has carried on its campaign of missile and drone attacks in Ukraine, with at least eight people killed in the eastern Donetsk city of Lyman on Saturday.

Lyman is a key railway hub and initially fell to Russia after the invasion, but was retaken by Ukraine's army in October.