There is now a "strong belief" that a group of 13 Ukrainian border guards thought to be dead are actually still alive, officials have stated.

On Thursday, a small group of 13 border guards defending Ukraine's small Zmiinyi Island (Snake Island) were believed to have died after being confronted by a Russian warship.

As reported by BBC News, Ukrainian President Volodymyr Zelenskyy said on Thursday that all 13 border guards "died heroically" as a result of sea and air strikes, and that the country would be honoring each of them with the posthumous title of "Hero of Ukraine".

Russia denied the claims, with BBC News stating that Russia's account of the story differs dramatically from what has been reported elsewhere.

According to BBC News, Moscow has said there were 82 Ukrainian soldiers on the island at the time, with all of them surrendering voluntarily. Russian officials added that there was never any mention of a sea or land strike and there were no casualties.

The story went viral on social media after a leaked audio exchange - allegedly between the Russian aboard the warship and the Ukrainian border guards - was shared by Ukrainian government officials.

You can listen to the audio exchange below:

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In the audio - which The Independent reports has been verified by Ukraine’s interior ministry - the Russian warship can be heard telling the border guards: "I propose you lay down your weapons and surrender to avoid bloodshed and unnecessary victims. Otherwise, you will be bombed."

In response, a Ukrainian border guard on the island responded by saying: "Russian warship, go f*** yourself."

However, despite initial beliefs that all border guards perished in the alleged attack, the State Border Guard Service of Ukraine (SBGSU) said on Saturday, per The Independent: "We [have a] strong belief that all Ukrainian defenders of Zmiinyi (Snake) Island may be alive."

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In a post shared to the SBGSU Facebook page, officials wrote: "After receiving information about their possible location, the [border guard service] together with the Armed Forces of Ukraine are conducting work on identifying our soldiers."

"Preliminary information that border guards may be dead came before the defenders lost contact," the post continued, adding: "We sincerely hope that the boys will return home as soon as possible, and the information received at the time of the attack on the death will not be confirmed. Glory to Ukrainian defenders."

Zmiinyi Island - known as Snake Island - is located in the Black Sea approximately 30 miles (48 kilometers) off Ukraine's southern coast. Its total land area measures less than one-tenth of a square mile, per Insider.

Featured image credit: imageBROKER / Alamy

'Strong belief' that Ukrainian border guards that told Russian warship 'go f*** yourself' are still alive, officials say