Papachristo has been expelled from the London Games by Greece for her Twitter comments on African immigrants and expressing support for a far-right party.
Papachristou was to compete in her first Games. The 23-year-old is from Athens.
The IOC has strict guidelines on what athletes can say in social media. This is the first case of an athlete being expelled from an Olympics for social media use.
The Tweet that got Papachristou in trouble was posted July 22: "So many Africans in Greece at least West Nile mosquitoes will eat homemade food"
Fifty-four people marked it as a "favorite" on Twitter.
She apologized on Twitter and Facebook, saying that her comment was a joke. "I would like to express my heartfelt apologies for the unfortunate and tasteless joke I published on my personal Twitter account. I am very sorry and ashamed for the negative responses I triggered, since I never wanted to offend anyone, or to encroach human rights.
