Usyk was urged to "fight for the country", with the bout scheduled for August 20 in Saudi Arabia.

The Ukrainian won the first professional fight between the pair in London last year, to remain undefeated in 19 bouts.

Both claimed gold medals in the under-91 kilogram and over-91kg categories at the London 2012 Olympic Games.

Following the invasion of his country by Russia - with assistance from Belarus - Usyk returned to Ukraine by joining a territorial defence battalion in Kyiv.

He was initially reluctant to leave, but in March the Ukrainian Sports Ministry said it would grant him permission to leave to fight Joshua.

"I really didn't want to leave our country, I didn't want to leave our city," said Usyk to reporters, according to Reuters.

"I went to the hospital where soldiers were wounded and getting rehabilitation from the war.

"They were asking me to go, to fight, to fight for the country, fight for your pride and if you're going to go there, you're even going to help more for our country.

"I know a lot of my close people, friends, close friends, are right now in the front line and fighting. 

"What I'm doing right now, I'm just supporting them, and with this fight, I wanted to bring them some kind of joy in between what they do."

On February 24, Russia invaded Ukraine, leading the International Olympic Committee to recommend the banning of athletes and officials from Russia and Belarus at international competitions.

This ban is in force at several International Federations - including the amateur body, the International Boxing Association - while others are allowing the athletes to compete under neutral banners.