An ambassador for Laureus Sport for Good, Shevchenko surprised children who had fled the war with a visit to a school in Warsaw.

The world has rallied around Ukraine amid Russia's invasion, with sporting stars and celebrities using their platform to raise awareness of the situation in the country.

On Sunday (AEST), WTA world number one Swiatek organised a charity tennis match, where Shevchenko was a special guest, while Lewandowski has been vocal in his support – and will wear a Barcelona shirt featuring the UNHCR logo, the United Nations' main agency for refugees, this season.

After his appearance in Warsaw, Shevchenko thanked Poland as a nation for taking in a flood of refugees from its European neighbour.

"I want to thank you, [the] Polish people, for being very kind to my country. For hosting us here. For providing all the needs," he said, as per Laureus Sport for Good.

"Thank you so much for your support. Also, I want to thank Iga Swiatek and Robert Lewandowski for taking a big part in initiatives helping my country to raise the funds and support against the war in Ukraine."

Shevchenko also praised compatriot Oleksandr Zinchenko for speaking out against the war, something numerous Ukrainian athletes have done.

"Like many, everyone Ukrainian, his reaction against the war, he stood up and then he spoke loud," he added of Zinchenko, who last week signed for Arsenal from Premier League champion Manchester City.

"He expressed his view, he's expressed his very hard feelings against the war for Ukraine, because he loves Ukraine, he loves people. 

"And we did a lot of activities together, we've been involved in a few fundraisers. I know he's a very generous person and he did a lot for Ukrainian people."