The country's home secretary questions the foundation of modern asylum law during a speech in Washington.
Suella Braverman questioned the United Nations Refugee Convention in a speech in Washington, arguing that "simply being gay, or a woman" should not be by itself grounds for international protection.
The British government has made the fight against illegal immigration a priority.
With a general election due next year, which the opposition party Labour is widely tipped to win, the ruling Conservatives' stance against asylum seekers is becoming increasingly hardline.
Some Labour politicians claim the Tories are scapegoating vulnerable groups to distract from their own failings in government.
Speaking at the American Enterprise Institute, the UK home secretary questioned the role of the 1951 Geneva Convention, which defines refugee status.
She said it was an incredible achievement for its time "but we now live in a totally different era".
The right-winger added that it's up to political leaders to ask themselves whether the convention, and the way it's been interpreted by the courts, is fit for "modern times".
"Let me be clear, there are vast swathes of the world where it is extremely difficult to be gay, or to be a woman," she said. "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."
In 12 countries around the world, people can be put to death for having a same-sex relationship, while in 66 states private, consensual same-sex sexual activity is criminalised, according to the Human Dignity Trust.
Braverman called the current situation "absurd and untenable", claiming it allows migrants to "choose their preferred destination to apply for asylum."
"No one entering the UK by boat from France is fleeing imminent peril", continues the text of the speech.
Yvette Cooper, of the Labour Party, accused Braverman of having "given up on fixing the chaos caused by the Tories" on asylum law and of looking "for someone else to blame".
Under the Conservative government, the number of people in the UK asylum system has reached record levels.
Experts say one reason for this is that officials have failed to process applications in a timely manner, causing a huge backlog to build up.
In a statement, the Refugee Council said the British government should "tackle the real problems facing the asylum system and provide safe routes for people in need of protection" rather than attacking the Geneva Convention.
Set up after the devastation of World War Two, the 1951 Geneva Convention is an international treaty that established the rights and protections for refugees, aiming to provide sanctuary and support to those fleeing persecution and violence.
The British government has promised to stop migrant boats crossing the Channel from France.
The law now prohibits migrants who have arrived in the UK illegally from applying for asylum. The government wants to deport them to third countries such as Rwanda, a project currently blocked by the courts.