Updated

Campus officials at Colorado State University have penned a letter to parents, asking them to speak to their kids about the potential risks of the unsanctioned “Undie Run” on school grounds this month.

The annual end-of-school-year event attracts thousands of runners, according to the Denver Post, including nonstudents and young high school students.

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Runners participate in a 2011 Undie Run in Salt Lake City.  (Fox News)

In the letter, officials at the Fort Collins-based school claim the run breeds an unhealthy atmosphere that includes drugs, drinking, property damage and potential sexual misconduct as many runners attend after-parties where they continue to wear just their underwear, the Post reported. The letter also cited concerns about spectators taking photos of students.

“Past participants, particularly women, have reported groping and sexual assault during the run and at after-parties. The run creates an environment where this sort of behavior more easily occurs.” the letter reportedly said.

“Past participants, particularly women, have reported groping and sexual assault during the run and at after-parties. The run creates an environment where this sort of behavior more easily occurs.”

— Colorado State letter to students' parents

Schools officials said runners have caused more than $150,000 in property damage over the years, according to the Denver Post.

The University of Colorado’s Boulder campus puts on a similar event, the Nearly Naked Mile, each year. The run is sanctioned by the campus and includes meetings on safety and a dance party hosted by the alumni association.

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CSU officials said law enforcement would be monitoring the run.

“If you touch others inappropriately, the university will choose to share your description or an image of you with the public in an effort to identify you and hold you accountable for your actions,” the university said, according to the Denver Post.