Once it passes, the law will likely mean anyone who arrives on small boats will be prevented from claiming asylum.

British lawmakers have approved a sweeping bill that will dramatically curb migrants’ ability to seek asylum in the United Kingdom, despite critics’ allegations that it breaks international law.

The Illegal Migration Bill was approved on Wednesday by the lower house of Parliament by a vote of 289 to 230, after the government accepted several amendments from rebel Conservatives, who claim it will deter tens of thousands of people from trying to reach the country each year.

It now goes from the House of Commons to the House of Lords, where it faces strong opposition — though the unelected upper chamber of Parliament can only amend or delay, but not block, the legislation.

Prime Minister Rishi Sunak has made this bill one of his five key priorities. Last year, the government made it a criminal offence for individuals to arrive in the UK without a visa or special permission.

Once it passes, the law will likely mean anyone who arrives on small boats will be prevented from claiming asylum and deported either back to their homeland or to a so-called safe third country, such as Rwanda.

They would be banned from ever re-entering the UK.

The large Conservative majority in the Commons ensured the bill’s passage there, despite opposition condemnation and claims legislators had not had enough time to scrutinise the legislation.

“This government has sought to railroad this deplorable, disgusting bill through the House of Commons,” said Stephen Flynn of the opposition Scottish National Party.

Critics and some charities have said the proposals are impractical and unethical, and demonise refugees.

They say people fleeing war and persecution can’t be sent home, and a UK plan to deport asylum seekers to Rwanda is mired in legal challenges, so migrants are set to languish in UK detention with no way out.

Lawmakers rejected several opposition amendments that would have watered down the bill, including changes to exempt pregnant women and children from detention.

The bill also bars people who are victims of human trafficking from using Britain’s modern slavery laws to prevent deportation.

The United Nations refugee agency has said the bill is a “clear breach” of the international Refugee Convention.

The British government has conceded there is a strong chance it breaches the UK’s international refugee and human rights obligations, but is determined to fight legal challenges.

Britain receives fewer asylum seekers than European nations such as Italy, Germany and France.

More than 45,000 people arrived in Britain in dinghies and other small boats in 2022, up from 8,500 in 2020.

Refugee groups say most of the channel arrivals are fleeing war, persecution or famine in countries including Afghanistan, Iran and Iraq, and risk the cross-channel journey because there are few safe, legal ways to reach the UK.

A majority of those whose claims have been processed were granted asylum in Britain.