Britain's immigration minister quit on Wednesday after the government published legislation regarding its controversial treaty with Rwanda to send migrants to the East African country.
Interior minister James Cleverly told lawmakers that Robert Jenrick had resigned, in a move that piles pressure on embattled Conservative Prime Minister Rishi Sunak.
Earlier on Wednesday Rwanda had warned that it would pull out of the treaty to accept migrants if the UK does not respect international law.
Foreign Minister Vincent Biruta, who signed the bilateral treaty on Tuesday, said any breach of global conventions could see Rwanda withdraw from the deal.
'Act lawfully'
"It has always been important to both Rwanda and the UK that our rule of law partnership meets the highest standards of international law, and it places obligations on both the UK and Rwanda to act lawfully," he said in a statement.
"Without lawful behaviour by the UK, Rwanda would not be able to continue with the Migration and Economic Development Partnership," he added, referring to the controversial deal.
The bill proposes giving ministers powers to disregard sections of the UK Human Rights Act and the European Convention on Human Rights when considering deportation cases.
Court injunction
The first deportees were due to be sent to Rwanda in June last year but were pulled off a flight at the last minute after a judge at the European Court of Human Rights issued an injunction.
Since then, their cases - and the wider legality of the policy - have been stuck in the courts.
Almost 30,000 irregular migrants have crossed the channel from northern France in rudimentary vessels this year.
