The UK government said a bill - expected to be announced Tuesday - will bar asylum claims by anyone who reaches Britain without prior authorisation, and will compel the government to detain and deport them "to their home country or a safe third country."

Prime Minister Rishi Sunak said the law would stop the “immoral” business of smuggling gangs who send desperate people on hazardous journeys across one of the world’s busiest shipping lanes.

Sunak has made stopping the boats one of his “five pledges” to voters, alongside halving inflation, kickstarting economic growth, slashing the national debt and cutting health care waiting lists.

Critics say the plan is unethical and unworkable, since people fleeing war and persecution can’t be sent home, and is likely to be the latest in a series of unfulfilled immigration pledges by successive UK. governments.

The British government says many of those making the journey are economic migrants rather than refugees and points to an upswing last year in arrivals from Albania, a European country that the UK. considers safe.

More than 45,000 people arrived in Britain by boat in 2022, up from 28,000 in 2021 and 8,500 in 2020. Most went on to claim asylum, but a backlog of more than 160,000 cases has led to many languishing in overcrowded processing centres or hotels, without the right to work.

Britain receives fewer asylum-seekers than some European nations — nine per 100,000 people in 2021, compared to a European Union average of 16 per 100,000. Thousands of migrants from around the world travel to northern France each year in hopes of reaching the UK

Most attempt the journey in dinghies and other small craft now that authorities have clamped down on other routes such as stowing away on buses or trucks.

Refugee groups say most of the channel arrivals are fleeing war, persecution or famine in countries including Afghanistan, Iran and Iraq. Most of those whose claims have been processed were granted asylum in the UK.

Refugee charities and human rights groups say many migrants risk the cross-channel journey because there are few safe, legal ways to reach the UK The government says it will establish more legal asylum — adding to those set up for Afghanistan, Hong Kong and Ukraine — but has yet to give details.

“The government’s flawed legislation will not stop the boats but result in tens of thousands locked up in detention at huge cost, permanently in limbo and being treated as criminals simply for seeking refuge,” said Enver Solomon, chief executive of the UK Refugee Council. “It’s unworkable, costly and won’t stop the boats.”