Belarusian tennis star Victoria Azarenka, a former world number one and two-time Grand Slam title winner, said Wednesday she is "devastated" by the violence "against and in Ukraine" following Russia's invasion of its neighbour.

The 32-year-old, who was a gold medallist for Belarus at the 2012 Olympics, is one of the highest-profile athletes from her country to hit out at the conflict.

"I am devastated by the actions that have taken place over the last several days against and in Ukraine," she wrote on Twitter.

"It is heartbreaking to see how many innocent people have been affected and continue to be affected by such violence.

"I have always seen and experienced Ukrainian and Belarusian people friendly and supportive of each other. It's hard to witness the violent separation currently taking place."

On Tuesday, the International Tennis Federation announced that Russia and Belarus would be suspended from the Davis Cup and Billie Jean King Cup competitions.

However, players can continue to compete at individual events.

Authoritarian Belarus and Russia are closely linked and Belarus has been used as a key staging ground for the invasion of neighbouring Ukraine.