Britain’s interior minister Suella Braverman said on Wednesday the government’s proposals to stop almost all migrants ever claiming asylum were legal despite warnings that the legislation would break international laws and be challenged in the courts.

Lawyers and charities said the plans would breach the United Nations convention on refugees, introduced after many countries turned Jewish refugees during World War Two.

Braverman wrote on the first page of the draft law that the plans could break the government’s Human Rights Act but said she included that statement “out of an abundance of caution.”

“We are confident that we are complying with the law, domestic and international,” she told the BBC. “But we are also pushing the boundaries and we are testing innovative and novel legal arguments.”

The new legislation is the latest in a series of contentious immigration policies put forward by the Conservative government under successive prime ministers aimed at stopping people arriving on England’s coast by small boats. Last year, the government announced a plan to send some of them to Rwanda.

Under the government’s plans, almost all asylum seekers who reach Britain in small boats will be detained without bail before they are deported to their home country or, if this is not safe, another destination such as Rwanda.

They will also lose the right to challenge their deportation while in Britain, and once deported will be automatically banned from returning.

Last year, a record 45,000 people came to Britain in small boats across the Channel, mainly from France. Prime Minister Rishi Sunak has said finding a solution is a top priority with the government spending more than 2 billion pounds ($2.4 billion) a year to accommodate them.

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Anger over immigration has played a defining role in British politics over the last decade and Sunak’s Conservatives hope that by taking a hard line they can rebuild their popularity as they trail the opposition Labor party by around 20 percentage points in opinion polls.

The legislation has been criticized as unworkable by opposition politicians and migration experts.

The United Nations refugee agency says the bill amounts to an “asylum ban” and is a clear breach of the UN refugee convention.

Sunder Katwala, head of the identity and immigration think-tank British Future, said in a blog post that “the pledge to detain and remove all people who cross the Channel has no prospect of being honored in the next two years.”

Plans to deport some asylum seekers to Rwanda have been stalled by legal challenges, including by the European Court of Human Rights, which last year blocked the first flight carrying detainees from taking off to Kigali.

In the absence of other agreements, this means tens of thousands of new arrivals could end up in detention. If everyone who arrived in small boats last year were detained, this would be equal to about half of Britain’s total prison population.

Braverman struggled to clarify if four-times Olympic champion Mo Farah would have been deported as soon as he turned 18 years old under the proposed regulations. Farah revealed last year that he was trafficked to Britain as a child.

She is also a critic of Gary Lineker, the former England soccer player and TV presenter, who said the government’s comments and plans were similar to those of Nazi Germany in the 1930s. She said his comments were “inappropriate” and “disappointing.”

That tweets and others in response to the bill prompted the BBC to say it would have a “frank conversation” with Lineker, who leads the network’s sports coverage and is bound to its impartiality guidelines.

—With additional files from the Associated Press