The UK government's controversial plans to stop the thousands of migrants arriving on British shores in small boats on Tuesday cleared their last parliamentary hurdle.

Members of the unelected upper house defeated a string of challenges to the government's Illegal Migration Bill - central to Prime Minister Rishi Sunak's pledge to "stop the boats" - at a late night sitting.

Members had proposed amendments relating to modern slavery protections and limits on how long child migrants can be detained but were voted down in a series of votes.

The bill - which will mean anyone arriving by boat will be refused the right to apply for asylum in the UK - will now become law following the formality of "royal assent" from King Charles III.

The legislation includes measures to transfer all irregular arrivals to "safe" third countries such as Rwanda to provide a deterrent against illegal migration.

More than 45,000 migrants arrived on the shores of southeast England on small boats in 2022 - a 60% annual increase on a perilous route that has been used by more people every year since 2018.

The Rwanda plan, announced by then-prime minister Boris Johnson last year, was blocked at the last minute by the European Court of Human Rights, which is separate to the EU, and is still mired in legal challenges.

The UK government last month said it would appeal a judgement by three Court of Appeal judges who ruled that Rwanda could not be considered a safe third country.

The ruling followed a challenge to the policy by 10 migrants and a charity supporting asylum seekers.

Sunak said he respected the court but "fundamentally" disagreed with the judges' conclusions.

To date, no deportation flights to Rwanda have taken place.

Rights groups accuse Rwanda - ruled with an iron fist by President Paul Kagame since the end of the 1994 genocide that killed around 800,000 people - of cracking down on free speech and opposition.