Last updated on .From the section Football
One of the highest-profile athletes still living in the country is a former captain of the Russia team.
Denisov earned 54 caps between 2008 and 2016 and called the invasion a catastrophe.
The ex-midfielder made the comments in an interview with sports journalist Nobel Arustamyan published on YouTube.
"Maybe they'll put me in jail or kill me for these words, but I'm telling it like it is," said the 38 year old.
Denisov said that he did not want to leave Russia and that he loved his country.
He wrote a letter to Putin expressing his opposition to the invasion.
I'm a proud man. Denisov said this was after a few days. I told him that I was going to go on my knees so that he could stop it all.
Most of the public figures in Russia are in favor of the military operation.
A player for the women's national team who now lives in Spain spoke out against the war.
Russian media can be fined or blocked if they use the words "war" or "invasion" to describe the situation in Ukraine.
During Denisov's interview with Arustamyan, certain words used to refer to Russian actions in Ukranian appeared to have been blanked out, with a crackling sound playing instead.
Sports.ru, one of the country's most prominent sports websites, did not use the words "war" or "invasion" when reporting Denisov's comments.