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The director of graduate studies for a Duke University School of Medicine department stepped down Saturday after screenshots of an email reported to be from her circulated on social media, suggesting students refrain from speaking Chinese to "improve their English."

"I encourage you to commit to using English 100 percent of the time" on campus or in professional settings, the email states.

Medical school dean Mary E. Klotman apologized to her students for the email, sent out by Megan Neely, director of the Master of Biostatics Program.

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"Dr. Neely has asked to step down as director of graduate studies for the master’s program effective immediately," Klotman said in a letter.

Neely's email, verified with a Duke spokesman by the campus newspaper, the Chronicle, said that two faculty members approached Neely to express disappointment that first-year students were speaking Chinese in student study and lounge areas.

"They were disappointed that these students were not taking the opportunity to improve their English and were being so impolite as to have a conversation that not everyone on the floor could understand," the email reads.

It goes on to urge students to keep these "unintended consequences in mind."

The email was roundly criticized on social media. NBC News reached out to Neely early Sunday but she did not respond immediately.

Klotman said in her letter to students that Duke's Office of Institutional Equity will investigate the matter.

"To be clear," she wrote, "there is absolutely no restriction or limitation on the language you use to converse and communicate with each other. Your career opportunities and recommendations will not in any way be influenced by the language you use outside the classroom."