The deaths of five people including a child while attempting to cross the English Channel underlines the need for the deterrent of the Rwanda scheme, Rishi Sunak has said.

The tragedy off the coast of northern France came just hours after Parliament passed legislation aimed at putting the Rwanda asylum scheme into effect.

The Prime Minister said criminal gangs were exploiting the vulnerable and “packing more and more people into these unseaworthy dinghies”.

At around 6am on Tuesday a dinghy carrying more than 100 people set off from Wimereux and got into difficulties.

Three men, a woman and a girl were killed, according to the French coastguard. Some 49 people were rescued but 58 others refused to leave the boat and continued their journey towards the UK, the coastguard said in a statement, adding that several other boats later embarked on the crossing.

The National Crime Agency said it would be supporting the French investigation into the deaths with UK police and Border Force.

During a flight to Poland, Mr Sunak told reporters the incident “underscores why you need a deterrent”.

He said: “We want to prevent people making these very dangerous crossings. If you look at what’s happening, criminal gangs are exploiting vulnerable people. They are packing more and more people into these unseaworthy dinghies.

“We’ve seen an enormous increase in the numbers per boat over the past few years.

“This is what tragically happens when they push people out to sea and that’s why, for matters of compassion more than anything else, we must actually break this business model and end this unfairness of people coming to our country illegally.”

Labour leader Sir Keir Starmer said it was an “absolute tragedy” and “a reminder that this vile trade run by criminal gangs costs lives”.

But “this Rwanda gimmick is not the way to stop it”, he said.

More migrants made the journey to the UK after an eight-day break in any crossings being recorded.

Young children and babies were among those seen arriving in Dover on Tuesday.

The incident at Wimereux occurred around four hours after the Safety of Rwanda (Asylum and Immigration Bill) cleared Parliament.

Preparations for the first flights to Rwanda will begin within days, with asylum seekers who could be relocated being identified and potentially detained.

Charter planes are expected to leave for Rwanda in 10-12 weeks, with Mr Sunak promising “multiple flights a month”, although minsters conceded numbers being sent to Kigali will be small at first.

Some £290 million has already been committed to the Rwanda scheme, with a further £100 million earmarked over the next two years.

The cost of putting each migrant on a plane is expected to reach £11,000 while Rwanda will get £20,000 for each asylum seeker relocated there and a £120 million top-up once 300 have arrived.

The Prime Minister said: “The passing of this landmark legislation is not just a step forward but a fundamental change in the global equation on migration.”

He said the Government’s focus was now on getting flights off the ground “and I am clear that nothing will stand in our way of doing that and saving lives”.

Mr Sunak has insisted he will not let the European Court of Human Rights block flights to Rwanda.

The court is an institution of the Council of Europe, which urged Mr Sunak to abandon the Rwanda plan.

The council’s human rights commissioner, Michael O’Flaherty, said: “The United Kingdom Government should refrain from removing people under the Rwanda policy and reverse the Bill’s effective infringement of judicial independence.”

The United Nations has also called on Mr Sunak to rethink the scheme.

Filippo Grandi, the UN High Commissioner for Refugees, said: “The new legislation marks a further step away from the UK’s long tradition of providing refuge to those in need, in breach of the Refugee Convention.”

The charity Freedom from Torture, alongside Amnesty International and Liberty, criticised the Government for ignoring the findings of the Supreme Court, which ruled in November that the policy was unlawful.

The groups said the Bill poses “a significant threat to the rule of law” by undermining what protects people from an abuse of power by the state, and described Parliament as a “crime scene”.

Ministers are braced for legal challenges to the scheme and the judiciary has made 25 courtrooms available to deal with cases.

But the Government believes the new law will dramatically restrict the ability of migrants to legally avoid being sent to Rwanda.

After the Safety of Rwanda Bill receives royal assent – expected in the coming days – the process of ratifying a treaty drawn up with Rwanda will begin.

The Lords backed down after MPs rejected a requirement that Rwanda could not be treated as safe until the secretary of state, having consulted an independent monitoring body, made a statement to Parliament to that effect.

Lord Anderson, the crossbench peer responsible for the call, said: “The time has now come to acknowledge the primacy of the elected House and to withdraw from the fray.”

Earlier in the upper House, Labour did not press its demand for the Bill to include an exemption from removal for Afghan nationals who assisted British troops, after what critics hailed as a concession.

The Government promised it will not send those who are eligible under the Afghan Relocations and Assistance Policy (Arap) to Rwanda.

Shadow home secretary Yvette Cooper called the Bill “an extortionately expensive gimmick rather than a serious plan to tackle dangerous boat crossings”.

Rwandan government spokeswoman Yolande Makolo said: “We are committed to the migration and economic development partnership with the UK and look forward to welcoming those relocated to Rwanda.”