Foreign students studying for most masters degrees will no longer be able to bring family members to the UK, under an immigration clampdown.
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 – almost nine times the figure for 2019.
Prime Minister Rishi Sunak recently said legal migration was too high.
Last week, he said ministers were “considering a range of options” to bring migration down, but refused to put a precise figure on future acceptable levels.
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 latest announcement, partners and children of graduate 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.
Last year, the 135,788 visas granted to dependants made up more than a fifth of all sponsored study-related visas granted, compared to 6% in 2019.
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”.
The prime minister told cabinet ministers the change, which will come into effect in January 2024, would make a “significant difference” to net migration numbers.
Students coming to the UK with a visa need to provide documents proving their relationship to dependents, who have to pay £490 for a visa.
Dependants are also required to pay the immigration health surcharge – an annual contribution between £470 and £624 towards NHS services.