In a move to alter an agreement that undermined UK plans to send asylum seekers to Rwanda, the home secretary will argue that the United Nations 1951 refugee convention must be reformed to tackle a worldwide migration crisis.

She will argue that case law arising from the convention has lowered the threshold so that asylum seekers need only prove that they face “discrimination” instead of a real risk of torture, death or violence. As case law has developed, she will say, there has been “an interpretive shift away from ‘persecution’, in favour of something more akin to a definition of ‘discrimination’”.

Speaking to the American Enterprise Institute, a rightwing thinktank in Washington DC, Braverman will say the change has expanded the number of those who may qualify for asylum to “unsustainable” levels, adding: “Let me be clear, there are vast swathes of the world where it is extremely difficult to be gay, or to be a woman.”

“Where individuals are being persecuted, it is right that we offer sanctuary. But we will not be able to sustain an asylum system if in effect, simply being gay, or a woman, and fearful of discrimination in your country of origin, is sufficient to qualify for protection,” she will say, in pre-briefed comments that have already drawn fire.