The number of international students in the US fell by 2.2?per cent at undergraduate level and 5.5?per cent at postgraduate level from 2016 to 2017, according to??from the National Science Foundation, Science and Engineering Indicators.

The analysis is based on government-held student visa data and excludes students who are participating in optional practical training, a programme that allows international students to stay and work in the US for up to three years after graduating while remaining on their university's sponsorship.

The declines come on the heels of years of steady growth in overall international enrolments at US universities and amid widespread concern that prospective new students could be deterred by the current political climate and uncertainty about immigration policies in the country.

The declines, if they were to continue, could have negative implications for US competitiveness and the health of American postgraduate science and engineering programmes, which are heavily populated by international students. In 2015, international students made up 36 per cent of all science and engineering postgraduate students in the US and received more than half of all doctoral degrees awarded in computer science, economics, engineering, and mathematics and statistics.

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The student visa-sourced data provide the first comprehensive national picture of international enrolments for the current academic year. It differs from an annual report on international enrolment conducted by the Institute of International Education, called Open Doors, which surveys universities about their international enrolments and reports the data on a one-year lag.

In November,??in the 2016-17 academic year and an overall flattening of growth.

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A companion "snapshot" survey IIE conducted in association with other academic groups asked about 500 institutions about their international enrolments for the current academic year. Overall, the universities in the survey reported an average decline in new international enrolments of 7?per cent. But the declines weren't being felt across the board: while 45?per cent of institutions responding to the snapshot survey reported declines in new international students, 31?per cent reported increases and 24?per cent reported no change.

Among the reasons university officials have given for the declines in international student enrolments are the political and social environment in the US, the high cost of US higher education, visa denial and delays, increasing competition from other countries and changes to other governments' scholarship programmes, such as Saudi Arabia's.

This is an edited version of a story which .