Prime Minister Rishi Sunak has made stopping boat arrivals one of his five key priorities after the number of migrants arriving on the south coast of England soared to more than 45,000 last year, up 500 per cent in the last two years.

The new legislation will mean anyone who arrives this way will be prevented from claiming asylum and deported either back to their homeland or to so-called safe third countries.

The United Nation’s refugee agency said it was “profoundly concerned” by the proposals, which would deny people the right to asylum “no matter how genuine and compelling” individual cases may be.

The government said on the first page of the draft legislation that it may not be compatible with the UK’s obligations under the European Convention on Human Rights, meaning it could face legal challenges if made into law.

Sunak said he would do “whatever is necessary” to stop the small boats and was ready to fight any legal challenges.

“We’re up for the fight, I wouldn’t be standing here if we weren’t – but we’re actually confident that we will win,” he told a press conference, standing in front of a lectern with a sign stating “STOP THE BOATS”.

The legislation will allow the detention of migrants without bail until they can be removed, interior minister Suella Braverman said, and those entering the UK illegally would no longer be able to use anti-slavery laws to try to block removal.

Only children, people who are considered too ill to fly or those at a “real risk of serious and irreversible harm” will be allowed to claim asylum in the UK.

Just under two-thirds of those who arrive on small boats are currently granted asylum or another form of humanitarian protection, interior ministry figures show.

While the number of applications for asylum in the UK hit a 20-year high of nearly 75,000 in 2022, it is still below the European Union average.

Germany received more than 240,000 asylum applications last year.

Opposition parties and charities have questioned whether the latest plans would be any more effective than previous attempts in the last decade to deter people from making the crossing.

Labour’s home affairs spokeswoman Yvette Cooper described the government’s announcement as another “Groundhog Day” and said it should be working with other countries to address the matter.

Last year, the UK agreed a deal to send tens of thousands of migrants more than 6400km to Rwanda.

The first deportation flight was blocked by an injunction from the European Court of Human Rights.

London’s High Court then ruled it lawful in December but opponents are seeking to appeal that verdict.

Braverman said she was in discussions with the European human rights court to halt the use of injunctions to prevent the future deportation of migrants.

She suggested to parliament that without changes to the law, 100 million asylum seekers could qualify for protection in the UK but did not provide supporting evidence for that figure.

-AAP