DURHAM, N.C. -- Duke University moved quickly Monday to offer apologies, launch an investigation and reassure a core group of graduate scholars after a medical school administrator sent an email warning Chinese students to speak in English.

The administrator's message -- which suggested students could face consequences -- came at a time when Duke and other elite U.S. universities are working hard to remain attractive to top international students despite negative rhetoric toward foreigners by President Donald Trump and other politicians.

"Duke's engagement with China, with Chinese students and with Chinese scholars is broad, deep and longstanding," Duke Vice-President for Public Affairs Michael Schoenfeld said in an interview Monday.

"We deeply regret that this particular incident might have compromised the very valuable and mutually beneficial relationship that Duke has with its Chinese students."

Across all of Duke's graduate and professional programs, 1,300 of about 8,500 students come from China, according to university data. Duke also partners with Wuhan University on Duke Kunshan University in China, which began enrolling students in 2014.

Outcry mounted after an email sent Friday by Megan Neely, who teaches in the biostatistics master's degree program and served as its director of graduate studies.

Neely's message to an email list for about 50 biostatistics students said two faculty members approached her to complain about students loudly speaking Chinese in a common area. She wrote that both were disappointed the students weren't working to improve their English and wanted their names. The email urged international students to "keep these unintended consequences in mind when you choose to speak in Chinese in the building."

She had also sent an email last February to students saying that "many faculty" noticed students were speaking other languages in break rooms.

"As a result they may be more hesitant to hire or work with international students because communication is such an important part of what we do as biostaticians," she said in the email.

Since the weekend, screenshots of the emails and stories about them have received wide attention in the U.S. and China. The thousands of comments on Chinese social media included some calls for Chinese universities to ban speaking English.

A petition demanding a thorough investigation has drawn more than 2,000 signatures of students, alumni and others, organizers said.

The Duke Asian Students Association also issued a statement slamming Neely's emails as discriminatory and harmful.

"For international students, speaking in their mother tongue is a means of comfort and familiarity with a home and culture that is already oftentimes suppressed within the United States," the association said.

Amid the angry response, Neely stepped down as the program's director of graduate studies, according to a letter from Dr. Mary Klotman, the medical school dean.

Klotman apologized to students in the program in her letter, saying there was no restriction on using foreign languages in conversations. She said the university's Office of Institutional Equity would conduct a review of the biostatistics master's program. It's expected to examine which faculty members complained to Neely.

Neely, who remains an assistant professor, also apologized in an email to program members, saying: "I deeply regret the hurt my email has caused. It was not my intention."

Thirty-six of the 55 students in the biostatistics master's degree program are from China, and Chinese scholars represent one-fifth of the program's approximately 50 faculty members, Duke said.

International students are particularly attractive to U.S. graduate programs because many countries abroad place more emphasis on math and science education, and because foreign students with the means to study in the U.S. often can pay full tuition rather than seek financial assistance, said Scott Jaschik, the editor of Inside Higher Ed.

He commended Duke for moving quickly to investigate, but said the school's reputation could still suffer.

"There is a quite a grapevine of information about international students back home," he said in an interview. "You can be sure people will hear about this."

Chi Liu, who's pursuing a chemistry PhD at Duke, said the university can maintain a good reputation abroad if it shows it's taking the situation seriously. Liu, who's from China's Hunan Province, believes Duke should fire Neely and the two unnamed faculty members who complained to her.

"All of us are angry. We feel offended," he said, referring to the reaction among students from China. "You have this email to the Chinese students saying ... if you speak Chinese you will be remembered and identified, and that will affect your performance. That is very serious."

Diana Sojda, a 27-year-old Duke nursing student, said language used outside of the classroom shouldn't be restricted. Sojda grew up speaking Spanish in her Chicago household with a mother from Mexico and a father from Poland.

"It's their free time, so they should be able to talk among themselves in whatever language they feel most comfortable with," she said.

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Associated Press researcher Shanshan Wang in Beijing contributed to this report.