The Colorado school that barred a gay valedictorian from coming out during his commencement speech denies it discriminated against the teen, and says no discussion of sexual orientation is appropriate for a graduation ceremony.

In a letter released Tuesday, the Twin Peaks Charter Academy in Longmont announced it was conducting an internal review of what happened after Democratic U.S. Rep. Jared Polis of Colorado requested a probe. In a letter to the school dated Friday, Polis cited media reports that Evan Young, 18, was not allowed to give his speech at his May 16 graduation solely on the basis of his sexual orientation and was denied recognition of his academic achievements.

School board president Kathy DeMatteo, writing to Polis, said officials do not "believe that a discussion of a student's sexual orientation — no matter what that sexual orientation happens to be — is a proper matter for a commencement address. It beggars belief that you do."

DeMatteo said Young was barred from delivering his speech not because he is gay but because of his "apparent intention to make a mockery" of the ceremony, and said his academic achievements were recognized in the event's program and at another gathering.

In a statement Wednesday, Polis called for an independent investigation, saying school officials already had made up their minds and were "throwing Evan under the bus."

The events in Longmont contrast with a decision by another Colorado school to allow its high school valedictorian to come out in her graduation speech. During her weekend speech in Carbondale, Roaring Fork High School graduate Emily Bruell received a standing ovation. Her principal, expressing concern about the high rates of suicide and other problems encountered by teens labeled as different, praised Bruell's courage and said her speech would help all his students feel safe and accepted at school .