Thousands more Britons will be barred from bringing their foreign husbands and wives to the UK, under plans in the Conservative manifesto.

The next Tory government would hike the minimum income requirement already attacked as “particularly harsh” by Supreme Court justices.

A further crackdown on immigration would also “toughen the visa requirements for students” – firmly crushing cabinet opposition to including students within the target to reduce incomers.

The current threshold to bring in spouses of £18,600, introduced by Theresa May as Home Secretary, has been blamed for inflicting a harsh choice of separation or living in exile on British families.

Campaigners have highlighted the plight of up to 15,000 children who have grown up as “Skype kids”, in order to keep in contact with one of their parents.

The manifesto reads: “We will increase the earnings thresholds for people wishing to sponsor migrants for family visas.” But it does not set out a new minimum amount.

It makes clear that the move would be an attempt to help the Conservatives reach their widely-ridiculed target of reducing net immigration to the tens of thousands.

“We will, therefore, continue to bear down on immigration from outside the European Union,” it says.

In 2015, it was estimated that the £18,600 threshold excludes 41 per cent of the British working population from bringing a foreign spouse to live in Britain, including 55 per cent of women.

The threshold rises to £22,400 if there is one or more non-European-born child in the family – and the income of the non-European partner does not count towards the threshold.

In February, the Supreme Court ruled that the minimum income threshold is legal, but warned that it had caused hardship for thousands of couples.

Labour has said it would scrap the threshold, stating it does not believe that “family life should be protected only for the wealthy”.

The section of the manifesto devoted to immigration also makes clear that trying to reach the target would involve a further squeeze on foreign students.

“We will toughen the visa requirements for students, to make sure that we maintain high standards,” it states.

“We will expect students to leave the country at the end of their course, unless they meet new, higher requirements that allow them to work in Britain after their studies have concluded.