An American schoolgirl was expelled from her Christian school after posting photos of her celebrating her 15th birthday with a rainbow cake and in a rainbow jumper.

Kayla Kenney from Kentucky celebrated her birthday with her family at a local restaurant, her mother Kimberly Alford took the photo and put it on social media to celebrate.

A few days after the photo was taken, the head teacher of the private Christian school, Whitefield Academy contacted Kayla's family on 6th January via email to let tell them Kayla had been expelled by the school with immediate effect, for the picture that 'demonstrates a posture of morality and cultural acceptance contrary to that of Whitefield Academy's beliefs.'

Kayla's post did not allude to any relation with the LGBTQ Pride movement, which bears the rainbow flag symbol. 

Alford told Kentucky news site WAVE3 there was no hidden agenda or meaning behind the picture - her daughter was simply celebrating her birthday. 

"[Kayla] loves to laugh and dance and that's just her. There was nothing intended by that and even when I went back and got the receipt from the bakery, it didn't say anything about representation, it just said assorted colours," she said.

The school claimed the picture was the latest stint in two years' worth of 'lifestyle violations'.  

Alford says she does not know how the school came to its conclusion and has filed an appeal against the expulsion. 

According to WAVE3, school administrators have refused to meet with Kayla and her family. 

The school, where tuition costs $7,800 a year did agree to list her withdrawal from the school as voluntary so it will not show on her school record. Kayla now attends a public school.