The principal of a private school in Alice Springs has apologised after a student who came to a Book Week assembly dressed as Adolf Hitler was named as being among the best dressed.

The principal of St Philip's College, Roger Herbert, said the school deeply regretted the decision to allow the student to come dressed as Hitler at a special assembly for Book Week, which occurred in front of a group of exchange students from a Jewish school in Melbourne.

Mr Herbert said the boy got up as one of the "best dressed" people at the assembly.

He said he had apologised to both the Jewish students and the principal of Bialik College in Melbourne, who had accepted his regret.

"We got them together and apologised and they were fantastic, absolutely fantastic, and accepting," Mr Herbert told 783 ABC Alice Springs.

"We also contacted the school to say look, this had happened, please understand."

The student had been given permission from a teacher prior to arriving at the school dressed as Hitler.

"In a busy school, this student did go to a respected staff member said 'is this OK?' and the staff member said 'yes'," Mr Herbert said.

"Now she is absolutely shattered that she said that, and I'm really concerned about her wellbeing."

Bialik College principal Jeremy Stowe-Lindner said it was an unfortunate incident but children were unpredictable and St Philip's had taken the right action since the incident.

"I understand that no malice was intended and I guess the coincidence of Jewish children visiting from Melbourne is a learning opportunity for the community, and that the principal assures me this is number one priority," Mr Stowe-Lindner said.