The athlete was dropped from the London 2012 Games days ahead of the event's launch on Friday (27Jul12) after she posted a message which caused outrage on the microblogging website.
Papachristou reportedly wrote, ""With so many Africans in Greece, at least the mosquitoes of West Nile will eat homemade food"", but later deleted the message.
Furious team bosses have axed her from the squad over the scandal and condemned her comments in a statement, branding the tweet ""contrary to the values ??and ideals of the Olympic movement"".
In a statement on Wednesday (25Jul12), Papachristou says, ""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.
""My dream is connected to the Olympic Games and I could not possibly participate if I did not respect their values. Therefore, I could never believe in discrimination between human beings and races.
""I would like to apologize to all my friends and fellow athletes, who I may have insulted or shamed, the National Team, as well as the people and companies who support my athletic career. Finally, I would like to apologize to my coach and my family.""