Boxing great Klitschko - best known on the professional circuit alongside brother Vitali as two of the best heavyweight fighters of all time - has volunteered to serve in the Ukrainian Army, joining the Kyiv Territorial Defense Brigade.

Wladimir was the super-heavyweight Olympic gold medallist from the Atlanta 1996 Games before having a professional career where he retired in 2017 with a record of 64 wins and five losses.

Mayor of Kyiv, Vitali has also joined the forces.

He was supposed to compete at Atlanta 1996, but failed a drugs test in the build-up to the Games, meaning he was dropped from the team.

He also had a professional career with 45 wins and two losses and became the Mayor of the capital city in 2014.

"We're not interested in how strong the Russian army is, we’re ready to fight," said Vitali to CNN.

"And we're ready to die for our home country and for our families, because it's our home.

"It's our future and somebody wants to come to our home and steal our future from us."

Vasily Lomachenko, a two-time Olympic boxing champion from 2008 and 2012, has taken up arms too - believed to be based near Odessa.

He has a professional record of 16 wins from 18.

Stanislav Horuna, karate bronze medallist from the Tokyo 2020 Olympics, asked for support for Ukraine on his 32nd birthday while announcing he had joined the armed forces too.

"Hello my friends," said Horuna on Instagram.

"It is the first of March, and today is my birthday.

"Just in case, if you wanted to make me a birthday present, better [to] send [that money] as a donation to support the Ukrainian Army and mention Ukraine in your social media.

"Thank you, stand with Ukraine."

He has shown videos of civilians making Molotov cocktails.

Ukraine's only Olympic gold medallist from Tokyo 2020, Zhan Beleniuk, is a sitting Member of Parliament, mentioning that he is armed in his office during the conflict, just seven months after becoming the nation's first black Olympic champion.

"I don't have any military experience but I have to be prepared," said Beleniuk, who has three pistols at his desk.

"One of the biggest problems we face is that Russian troops are blocking humanitarian corridors in many places so people are without food, without water, and they are actually dying of hunger and dehydration."

Ukrainian biathlete Bogdan Tsimbal was pictured sleeping in a bomb shelter with his infant son, just a couple of weeks after competing at the Beijing 2022 Winter Olympic Games.

Russia invaded Ukraine on February 24, breaching the Olympic Truce which led to the International Olympic Committee recommending the banning of athletes from Russia and its ally in the attack, Belarus.

Vladimir Putin, the Russian President, called the move a "special military operation".