Foreign postgraduate students on non-research courses will no longer be able to bring family members to the UK, under new immigration curbs.
The announcement has been made two days before official statistics are expected to show legal migration has hit a record 700,000 this year.
Last year, 135,788 visas were granted to dependants of foreign students, nearly nine times the 2019 figure.
PM Rishi Sunak told ministers the move would help bring migration down.
He told the cabinet that the change, to begin in January 2024, will make a “significant difference to the numbers,” according to No 10.
However, the impact it will have on official migration levels is unclear, since students and family members who come to the UK for less than a year are not counted.
Last week, he said ministers were “considering a range of options” to bring migration down, but refused to say what an acceptable level was.
The Conservatives have previously promised to bring net migration below 100,000 a year, but ditched the target ahead of the 2019 election after repeatedly failing to meet it.
Under the announcement, partners and children of postgraduate students other than those studying on courses designated as research programmes will no longer be allowed to apply to live in the UK during the course.
There were 135,788 visas granted to dependants last year, a rise from 54,486 in 2021, and more than seven times the 19,139 granted in 2020.
These figures have increased since study visa requirements for European Economic Area (EEA) students were introduced after Brexit.
Applications have also risen since rules were changed in 2019 to allow foreign students to stay in the UK for two years after graduating to look for jobs.
Home Secretary Suella Braverman said the rise in dependants being granted visas was “unprecedented,” and it was “time for us to tighten up this route to ensure we can cut migration numbers”.
In a statement to Parliament, she added that the move “strikes the right balance” between bringing down migration and “protecting the economic benefits that students can bring to the UK”.