Image copyright Duke University Image caption The course attracts students from a wide range of backgrounds

A US university professor has been removed as director of a graduate programme, amid a furore over an email she sent urging students not to speak Chinese.

Megan Neely, an assistant professor at Duke University in North Carolina, said in an email to students that two unnamed faculty members of the biostatistics Masters programme had complained to her about students speaking Chinese in public areas in the department.

She said that not speaking English could lead to "unintended consequences" for international students.

Her email went viral on Twitter and Chinese social media, while Duke's medical faculty has promised to review its biostatistics programme.

Many have criticised Dr Neely's email as racist or insensitive, and raised concerns that faculty members were discriminating against international students.

However, some ethnic minority students on the Masters programme told the BBC they supported Dr Neely, describing her as a supportive programme director and "definitely not a racist, not even close".

What exactly happened?

The controversy erupted after screenshots of Dr Neely's email to biostatistics students began circulating online over the weekend. Duke University confirmed to US media that the screenshots were genuine.

Dr Neely said that two faculty members had asked her if she had photos of students on the Masters programme, before picking out a number of first-year students "who they observed speaking Chinese (in their words, VERY LOUDLY), in the student lounge/study areas".

Dr Neely said that the faculty members told her "they wanted to write down the names so they could remember them if the students ever interviewed for an internship or asked to work with them for a masters project. 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.

"To international students," she continued, "PLEASE PLEASE PLEASE keep these unintended consequences in mind when you choose to speak in Chinese in the building."

She added that she respected international students for learning "in a non-native language", but "I encourage you to commit to using English 100% of the time when you are in Hock [the faculty building] or any other professional setting".

Image copyright Concerned Duke Students Image caption The petition was signed by 2,000 people by Sunday

Why was it so controversial?

The email went viral after it was leaked online and reported in the student paper The Chronicle. Many found the language in the email patronising, while others wondered if the students had been targeted because they spoke Chinese, rather than another foreign language.

For many, however, the most concerning part of the email was the allegation that two faculty members appeared ready to discriminate against students based on what language they spoke with their friends.

A group calling themselves Concerned Duke Students said in a petition that they were "gravely concerned" with the implication "that students of diverse national origin would be punished in academic and employment opportunities for speaking in their native language outside of classroom settings."

The group told the BBC that more than 2,000 people had signed their petition by Sunday, including current Duke students and alumni, as well as students from other institutions.

"We recognise that language difficulties could be a… barrier for many international students, but we think this is all the more reason why Duke should treat us with more respect and understanding," they said in a statement.

Mary Klotman, dean of the medical school which oversees the biostatistics programme, wrote to students over the weekend, telling them: "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. And your privacy will always be protected.

"I have asked the university's Office of Institutional Equity to conduct a thorough review of the Master of Biostatistics Programme," she added.

Dr Neely, who is still in post as an assistant professor, has not yet publicly commented on the controversy.

What do her students think?

As of Sunday night, millions on Weibo had viewed the hashtag "Duke University bans speaking Chinese", while "Duke University professor who banned speaking Chinese resigns" was the ninth-most trending hashtag.

One Weibo user described the email as "naked racism", while another joked: "Should we also chuck out any foreign exchange students who aren't speaking Chinese on campus, because they haven't taken advantage of the opportunity to learn Chinese in China?"

Meanwhile, several Twitter users began sharing Dr Neely's faculty photo or calling for her to be fired.

"This behaviour is not only hypocritical - given Duke's dependence on international students and faculty for their undergraduate and graduate programs - but also discriminatory," the university's Asian Students Association said in a statement.

"People should wholeheartedly be able to speak any language they wish - to strip away this agency is demeaning, disrespectful, and wholly discriminatory," it added.

However, others have argued that the furore has been overblown - or that Dr Neely has unfairly borne the brunt of the criticism.

One Weibo user suggested that the email had revealed deeper issues on the programme.

"I think this professor's actions may have been well intentioned, instead it might be the two faculty members who asked [for names and photos] who are the real racists," they wrote.

Three students on Duke's biostatistic masters programme, who asked not to be named, expressed support for her to the BBC.

"Dr Neely is a great instructor and definitely not a racist, not even close," one Chinese student said.

Another Chinese student told the BBC he had found Dr Neely "always willing to help" students of all nationalities, and hoped the university would investigate the two unnamed faculty members mentioned in her email instead.

A third student of Asian descent said: "Megan is truly the best instructor and mentor I ever had… She made a mistake [with her email], but we still know what was her intention and how much she cares about us.

"When some people talk loudly in foreign language, other people [in the lounge] are definitely disturbed."

The student added: "Some of my Chinese friends also told me they are worried that if they support Megan in the public, they might be regarded as 'people who betrayed their country' by other Chinese students in the United States."