American gymnast Simone Biles has thanked supporters after she announced her withdrawal from two Tokyo Olympics events to protect her mental health.

Biles pulled out of the women's team final on Tuesday after the first rotation, with her team going on to claim silver, as well as the all-round competition, which she won in Rio in 2016.

"The outpouring [of] love & support I’ve received has made me realize I’m more than my accomplishments and gymnastics which I never truly believed before," the 24-year-old superstar wrote in a tweet, which has received more than half a million likes and prompted hundreds of messages further backing the athlete.