Image copyright Getty Images Image caption In 2016-17, a total of 19% of students in higher education in the UK were from outside the country, according to official figures

A Home Office advisory committee has ditched research assessing the impact of international students after academics labelled it "unethical".

The survey, set up by the Migration Advisory Committee (Mac), which informs Home Office policy, asked for students' views on international classmates.

But it could be completed by anyone and some said it posed "loaded" questions.

A Mac spokesman stressed the survey was "not designed to be discriminatory", but confirmed it was being withdrawn.

"Following online commentary it has become apparent to us that we will be unable to use the responses to the survey," the spokesman said.

The committee defended the survey, saying it was "simply an attempt to ask students for their experiences" and "had the potential to show a very positive view of international students in the UK".

However, on Thursday, it concluded the survey "cannot now be used to add to our evidence base".

Prof Tanja Bueltmann‏, a professor of migration history at Northumbria University, said the survey was "completely invalid and must never be used as evidence to inform policy".

Is this fake?

She said she had urged the Home Office and the committee to scrap it or disregard it.

"Initially, I thought it must be some sort of fake thing - because of the nature of the questions," she said.

It asked students to assess whether the impact of international students on their course was negative, positive or neutral.

It also asked if students lived with any international students or studied with any on their course.

The survey was being posted by universities, who were encouraging students to fill it in and was due to close at the end of May.

It was also being shared on Twitter, by vice-chancellors from the Universities UK group, which later announced that it would no longer be sharing it.

A Universities UK spokesman said: "Due to legitimate concerns raised about a Migration Advisory Committee survey on international students, we will not be sharing it further.

"While it's important that policy-makers hear from students about international students' positive impact, views must be sought appropriately."

UUK vice-chancellors will also be deleting all tweets of the survey.

Prof Bueltmann said: "In principle there's nothing wrong with a survey on the impact of international students, but say you look Asian and you're actually British, but the student standing next to you thinks you're Asian?"

This could mean the person is basing their views on the wrong information, she suggested.

Image copyright HOME OFFICE Image caption An online message replaced the survey after it had been closed

Her view was mirrored by the Joint Council for the Welfare of Immigrants, which questioned whether the survey was "encouraging baseless speculation about those who seem different?".

The National Union of Students called the survey "inherently flawed".

The Union's international students' officer, Yinbo Yu, said asking students to gauge international student numbers "seemingly based on appearance" was "not only shockingly insensitive, but it does not reflect the reality of our diverse yet cohesive university communities".

Prof Bueltmann‏ also suggested that those who had a view that immigration was a bad thing would have been more likely to fill it in.

"It's a bit like with Tripadvisor, you're more likely to fill it in if you've had a bad experience," she said.

"The survey unquestionably contains loaded/leading questions that force respondents to problematise international students in a way that they may never have naturally done.

"If I had done this as a research project, I'd be in trouble with my ethics committee now."

She added that the whole design of the survey was flawed because anyone could fill it in, and repeatedly if they used different computers.

Posting on Twitter, Matthias Eberl, engagement lead at Cardiff University's Systems Immunity Research Institute, said: "A student survey that's openly accessible to anyone and can be filled in multiple times. Whatever the results from this survey, they are utterly meaningless."

A lawyer, Ewan Kennedy‏, also completed the survey, saying he found it "very odd".

He said he "went through it as an experiment and it shot off at the end without needing any identifier - oops!"

The survey was part of work commissioned by former Home Secretary Amber Rudd, after the government came under pressure to remove international students from net migration targets.

In her commissioning letter of August 2017, she said the committee had never undertaken a full assessment of the impact of international students.

"We would like to have an objective assessment of the impact of international students which includes consideration of both EU and non-EU students at all levels of education," the letter said.

"This assessment should go beyond the direct impact of students in the form of tuition fees and spending, including consideration of their impact on the labour market and the provision and quality of education provided to domestic students.

"This should give the government an improved evidence base for any future decisions whilst the ONS goes through the process of reviewing the contribution it thinks students are making to net migration."

Before the survey was decommissioned, a spokesman for the Mac had said it was part of its ongoing work looking at the impact of international students in the UK.