Not even her birthday will stop Simone Biles from calling out USA Gymnastics and holding them to account. 

The governing body tweeted the gymnast, writing: "HAPPY BIRTHDAY to the most decorated gymnast of all time, @simonebiles! We know you will only continue to amaze us and make history!"

She hit back straight away retweeting the message with a statement of her own: "How about you amaze me and do the right thing... have an independent investigation."

Biles was referring to the lack of action taken by USA Gymnastics following the revelation that team doctor Larry Nassar abused over 150 gymnasts in his care. Nassar was sentenced to up to 175 years in prison, two years ago, but USA Gymnastics hasn't been subject to an investigation.

This isn't the first time Biles has called out the organisation. Earlier in the month, she tweeted in exasperation with the situation while on her way to a training camp

The current settlement proposed by USA Gymnastics to resolve the 100 lawsuits they face due to their failure to protect the athletes against Nassar includes a $215 million payout. This would be split between 350 gymnasts represented by the cases. 

However, the proposals also include several clauses which absolve the organisation of responsibility – no member of the team has to accept liability, including former coaches and US Olympic officials. USA Gymnastics will also be allowed to withhold who knew about and hid Nassar's abuse.

Her call for an investigation was supported by her former teammate Aly Raisman who shared Biles' callout with the words: "This. Is. AWESOME." Raisman has also called out USA Gymnastics in the past.

Biles is the most decorated World Championships gymnast, with a total of 25 medals to her name. She is also a four-time Olympic champion.