Pupils at a school in Suffolk have been given letters telling them to stop making racist comments to fellow students from eastern Europe.
Ofsted inspectors found derogatory comments were being directed to pupils at Mildenhall College of Technology, who come from migrant families.
The college has acknowledged the problem and said its work to cut racism has seen a reduction in complaints.
Head teacher Terry Lewis said an influx of migrants had sparked racist remarks.
The 960-pupil school has 25 students from eastern Europe and a few from Asian backgrounds.
Tatiano Beato, a 17-year-old student whose parents moved to the area from Lisbon, Portugal, said she had been a victim of racism.
She said: "A lot of people used to tell me to go back to my country and were saying that I shouldn't be here.
"It made me feel really bad and I just wanted to leave. I think they thought I was different."
Terry Lewis said while racist comments were unacceptable, he believed its roots laid in the recent influx of migrant workers.
He added: "It's not unique to us, but I think the fact that there was never a significant ethnic minority of any description in our area, and a large influx of newcomers that brought out the attitudes that we need to combat.
"We believe it's part of our mission as a school to combat racism."
Apart from racism, Ofsted inspectors praised many aspects of the school.