Gyunduz Mamedov, a former deputy prosecutor-general, said that more than 3,000 athletes and coaches continued to fight for Ukraine.
"The death of the athletes is a heavy loss for Ukraine and its future," he said in a tweet on Monday, as cited by British broadcaster Sky News.
President Volodymyr Zelensky has said that many athletes have joined the ranks of the Ukrainian armed forces to defend their country on the battlefield.
Zelensky told the head of the International Olympic Committee, Thomas Bach, last year that more than 100,000 Ukrainian athletes were unable to train after many of the country's sports facilities were destroyed during the war.