An assistant professor at Duke University is stepping down from her post as director of a graduate program at the university's school of medicine after encouraging foreign students in an email to "commit to using English 100% of the time" on campus.

Megan Neely, who was director of the biostatistic graduate program, asked to leave her post Saturday after screenshots of her comments circulated online, according to The Chronicle, Duke's student-run newspaper. A school official confirmed to The Chronicle the authenticity of her email, which was sent to first- and second-year students on Friday.

Neely wrote that two faculty members had complained to her about a group of students who were "very loudly" speaking Chinese in a common area. She said the faculty members asked to see photos of masters students so they could identify the ones they heard speaking Chinese and "remember them if the students ever interviewed for an internship or asked to work with them for a master's project."

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"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," wrote Neely.

She warned about "unintended consequences" of speaking Chinese in the building and encouraged students to use English "100% of the time" in department areas and other professional settings.

Medical school dean Mary Klotman announced in an email that Neely had asked to step down from leading the graduate program "effective immediately." Klotman said she asked the school's Office of Institutional Equity to review the biostatistics program and recommend ways to "improve the learning environment for students from all backgrounds."

"There is absolutely no restriction or limitation on the language you use to converse and communicate with each other," Klotman wrote.

Neely will remain at Duke as a professor and researcher, according to Michael Schoenfeld, vice president of public relations and government affairs. The school did not say whether it identified the two faculty members who allegedly spoke to Neely about the students.

A student petition, which has received more than 1,000 signatures, asks for an independent investigation of Neely's emails and the actions of the unnamed faculty members she mentioned. The petition says Neely had previously sent an email in February 2018 titled "To Speak or To Not Speak English," in which she said "many faculty" had noticed international students weren't using English in break rooms. According to screenshots of that email, Neely wrote that using other languages "might not be the best choice while you are in the department," and that "speaking in your native language may give faculty the impression that you are not trying to improve your English skills."

Neely received her Ph.D. from North Carolina State University in 2011 and joined Duke that year as an assistant professor, according to her faculty profile. She did not return messages from CBS News.