Ukraine's Marta Kostyuk says shaking hands with Belarus' Victoria Azarenka after their US Open match would not have been "the right thing to do".

Belarus has been a key ally of Russia in the war against Ukraine.

"Everyone's trying to be super diplomatic about this thing. My nation is being killed daily," said Kostyuk.

Kostyuk, 20, criticised Azarenka's planned involvement in a Ukraine benefit event held in New York last week and the Belarusian later withdrew.

Azarenka said she wasn't "surprised" by Kostyuk's decision not to shake hands after their second-round match at Flushing Meadows.

"I don't believe that making a big deal out of it is important. I always shake hands with my opponents," said two-time major winner Azarenka.

Kostyuk was born in Ukrainian capital Kyiv, which has been a focal point of Russian attacks since the country invaded its neighbour in February.

The world number 65 has been one of the most vocal players to speak out about the war, regularly highlighting the devastating impact on Ukrainians caused by Russia's actions.

In April, she was one of several Ukrainian players who called for Russian and Belarusian players to be banned from the ATP and WTA Tours unless they publicly denounced the war.

"I feel like I don't know any single person who condemned the war publicly, and the actions of their government. I don't feel like I can support this," said Kostyuk.

"We had a great match, don't get me wrong. She's a great competitor, I respect her as an athlete but that has nothing to do with her as a human being."

Former world number one Azarenka has had a friendly relationship in the past with Belarusian president Alexander Lukashenko, who is a key ally of Russian counterpart Vladimir Putin.

Azarenka, 33, has not explicitly denounced the war, but has regularly called for an end to the conflict and says she wanted to take part in the US Open's 'Tennis Plays For Peace' event last week.

But, following criticism from Kostyuk and other Ukrainian players, the United States Tennis Association said Azarenka would not participate "given the sensitivities".

"It's a no-brainer for me. Like, why wouldn't I participate in a humanitarian aid for people who are really struggling right now. It's not even a thought for me at that moment," said Azarenka after her match with Kostyuk on Thursday.

"I thought this was a gesture that really shows commitment. I'm not sure why it wasn't taken that way. I don't want to judge that, that's what happened.

"I can't force it. I'm not going to go and say, 'Oh, how dare you?' It's not my place. My place is to be there to offer, offer my help, and that's it."