By David DeKok

HARRISBURG, Pa. (Reuters) - A Pennsylvania high school that warned graduating seniors to wear appropriate dress to an awards ceremony is being accused of imposing a double standard on female students and using language that some found degrading.

Biglerville High School, just north of Gettysburg, caused an uproar when it issued a letter advising female students to "choose modest attire” and keep "the girls" - a euphemism for breasts - covered and supported.

"Please remember as you select an outfit for the awards assembly that we don’t want to be looking at sausage rolls," the letter said. "As you get dressed, remember that you can’t put 10 pounds of mud in a five-pound sack."

While the school, which has about 500 students, warned female students against tight clothing, it only advised boys to wear nice clothes and avoid low-hanging pants.

Brianna Burtop, a senior who posted the school's letter to Facebook, told WHTM ABC 27 in Harrisburg that she was bothered by the language.

"You're supposed to feel safe and comfortable here. For a letter like that to come from the administration is really appalling," she said.

Her mother, Jessica Burtop, told the station the letter was "just totally wrong. It's totally degrading."

Wesley Doll, superintendent of Upper Adams School District, did not respond to a request for comment but his assistant emailed a statement Thursday in which the school backed away from the letter.

"While we regret that the document contained some unfortunate word choices, we do respect all students and hope this does not detract from the dignity of the graduation ceremony and the accomplishments of our graduating class," the statement read.

High schools around the country, including in Snellville, Georgia, and Declo, Idaho, have faced similar controversy this month, often over the issue of whether female students could wear slacks at graduation.

The Idaho ACLU sent a letter to all public high schools in the state urging them to avoid gender stereotyping in their graduation dress codes.

(Reporting By Frank McGurty; Editing by Bill Trott)