Suella Braverman has sought to play down speculation that her major speech this week on migration was an early bid to be the next Tory leader.

The Home Secretary insisted that such questions were “flippant” and that she was working “hand in hand” with Prime Minister Rishi Sunak.

The lengthy address in Washington to a centre-right think tank on Tuesday included calls for drastic reform of the United Nations’ Refugee Convention and warnings of the “existential threat” of uncontrolled migration.

It was seen by many in Westminster as an early leadership pitch by the senior Cabinet minister, who is a favourite of some MPs on the right of the party for her tough stance on illegal migration.

The same speech saw her also attack the “misguided dogma” of multiculturalism and saw her suggest that offering asylum to a person because they are discriminated against in their home country for being gay or a woman was not sustainable.

But Ms Braverman told the PA news agency that she had crossed the Atlantic to discuss a “serious issue” with US officials.

“With respect, that is a slightly flippant interpretation of what is a very serious issue.

“I am here meeting my US counterparts, talking about the epoch-defining challenge of illegal migration and I have set out my observations and my analysis of the problem, inviting international collaboration to find a joint solution.

“I think that is my duty as Home Secretary and I am pleased to be here in America raising the salience of the matter and working with partners.”

The visit saw Ms Braverman meet US secretary for homeland security Alejandro Mayorkas, with the pair jointly committing to exploring new ways to stop the spread of AI-generated images of child sexual abuse.

“I am here working as Home Secretary. I am very pleased to be working hand in hand with the Prime Minister to stop the boats, as he has pledged earlier in the year,” she said.

Ms Braverman is seen as one among the likely contenders on the right of the Tory party in the next leadership race, if Mr Sunak loses the next general election and is forced out by fellow MPs.