If adopted, the new bill would deny the right to seek refugee protection to people arriving irregularly in the UK, such as those risking their lives to cross the English Channel in small boats.
Instead, these asylum-seekers would face detention and deportation, without having their individual circumstances examined.
“This would be a clear breach of the Refugee Convention and would undermine a longstanding, humanitarian tradition of which the British people are rightly proud,” UNHCR said.
The UK is one of the original signatories of the 1951 Refugee Convention, which recognizes that refugees may have to enter a country of asylum irregularly.
According to UK Government figures, some 45,000 people crossed the Channel on small boats in 2022, up 60 per cent from the previous year.
The UNHCR Assistant High Commissioner for Protection, Gillian Triggs, tweeted that she was “profoundly concerned” by the UK bill introduced in the House of Commons on Tuesday.
In a statement, UNHCR noted that the UK is not part of any agreement that would allow authorities to share responsibility for refugees with safe third countries.
The UN agency also recalled that the UK’s bilateral arrangement with Rwanda announced in 2022 failed to meet the necessary international standards.
In June last year, the UN High Commissioner for Refugees dismissed the UK-Rwanda deal as “all wrong”.
UNHCR said it would continue to support the UK in strengthening its asylum system and urged the Government and legislators to reconsider the bill and “pursue more humane and practical policy solutions”.