Britain needs a decade of emigration to end the "age of being open to the world and his wife", Robert Jenrick has declared.
The top Tory, igniting an arms race with Nigel Farage on immigration, branded Boris Johnson's points-based system the "worst public policy mistake in my lifetime".
And he welcomed Reform's plan to deport 600,000 illegal immigrants, adding it must be a "priority" for the next Government.
But Mr Jenrick went even further than his political rival on the future of asylum accommodation, declaring that small boat arrivals should be detained in "rudimentary prisons", not "holiday camps".
In an explosive interview with The Spectator, published on Thursday, the former immigration minister declared: "Damaging though illegal migration is, legal migration is even more harmful to the country because of the sheer eye-watering numbers of people who have been coming across in recent years perfectly legally.
"It's putting immense pressure on public services.
"I think the country now needs breathing space after this period of mass migration. The age of being open to the world and his wife, who are low-wage, low-skilled individuals, and their dependents has to come to an end. Reversing recent low-skilled migration will likely mean a sustained period of net emigration.
"I would support that.
"Of course, we stay open to the very best and brightest. We want the coders, the doctors, the serial entrepreneurs, the people who are clearly going to make a massive economic contribution to the country.
"How long would this last? A decade? 'It could be, yes.'
Mr Jenrick, who resigned over Rishi Sunak's approach to legal migration, turned his fury on Boris Johnson and Priti Patel's immigration policies.
He declared: "At the Home Office I walked into a total bin fire. I think the points-based system that was created by the ministers at the time was the worst public policy mistake in my lifetime."
The Office for National Statistics said net migration to the UK hit 906,000 in the year to June 2023, amid an influx of foreign students, a spike in non-EU workers, particularly in the health and social care sectors and the introduction of the Ukraine and Hong Kong refugee visa schemes.
Tighter controls on overseas workers and foreign students led to a fall of 435,000 to 431,000, from a staggering 866,000 in the year to December 2023.
The Tories in 2023 banned overseas care workers and foreign students from bringing their family members with them to the UK.
The salary threshold for skilled workers was also increased to £38,700.
And Britain's asylum crisis has led to a further collapse in confidence in the Home Office.
The number of people claiming asylum hit 111,084 during Sir Keir Starmer's first year in office.
And Home Office records revealed the number of Channel migrants being deported has fallen under Labour. More asylum seekers are also living in taxpayer-funded hotel rooms, with 32,059 migrants in hotels - up 8% compared to when Sir Keir Starmer's Government came into office - after a surge in small boat arrivals.
Mr Farage has vowed to create a "UK Deportation Command" to identify every illegal arrival living in the UK, with five removal flights per day.
And he insisted Britain must leave the European Convention on Human Rights, repeal the Human Rights Act and ignore key refugee treaties.
He declared the UK would copy Donald Trump's mass-deportation programme by ordering Home Office Immigration Enforcement teams to carry out "large scale raids" across the country.
New "modular accommodation" will also be built to detain up to 24,000 people within 18 months of Mr Farage arriving in Downing Street, Reform said.

But Mr Jenrick, addressing the plans, said: "There's a lot to welcome' in Reform UK's plan.
"It's obviously going to be very important that we deport all the illegal migrants in the country and the next government has to make that their priority."
On asylum accommodation, he added: "They should be detained in camps.
"The facilities will need to be rudimentary prisons, not holiday camps. It's not what Reform have suggested, which is cabins with a fence around them."
The former Immigration Minister insisted Britain must use "every lever" of the state to remove illegal migrants.
He said: "We need to suspend visas and end foreign aid."
Pointing to Pakistan's refusal to take back three grooming gang members, Mr Jenrick added: "'At the same time, we're giving £130 million in foreign aid and tens of thousands of visas to Pakistan every year.
"That cannot be right. We should be open about the fact that we should send illegal migrants back to their home countries, even if in some cases those are inhospitable places."
Justice Secretary Shabana Mahmood declared that British judges take a "maximalist" approach to the European Convention on Human Rights.
Ms Mahmood warned the Strasbourg court it must consider reform or "there's no hope really at all, for anybody".
But she ruled out quitting the ECHR, amid calls to do so by Nigel Farage, Reform UK and the Conservatives.
Ms Mahmood said proposals over Article 8, the right to private and family life, will be brought forward later in the autumn and "may expand" beyond that.
She said: "Interestingly, if you talk to colleagues across Europe, there is a view that Britain is maybe more at the maximalist end of the spectrum when it comes to interpreting how we might comply with our international obligations.
"I think it's perfectly fine for us to question whether we have drawn the line in the right place, and the work that the Home Secretary is doing has both, you know, fresh guidance, secondary legislation or primary legislation all on the table as potential options.
"But as I say, the Home Office have done their immigration White Paper, where this work was a part of that and they will be seeing more a little later in the autumn about progress on that front."
Prime Minister Sir Keir Starmer said it would be a "profound mistake" to withdraw from the European Convention on Human Rights.
Ministers plan to tighten the use of Article 8 of the ECHR, the right to private and family life, in immigration cases in the UK. They are also exploring rule changes on Article 3, the right to avoid torture or degrading treatment, it is understood.
Sir Keir was responding on Wednesday to a question from Liberal Democrat leader Sir Ed Davey, who said: "The leader of the Conservative Party and the leader of Reform want to join Russia and Vladimir Putin by withdrawing from the convention.
"Will the Prime Minister categorically rule out withdrawing from the ECHR, or suspending it, or watering down our rights in any way?"
Sir Keir said: "We will not withdraw from the European Convention on Human Rights. We do need to make sure that both the convention and other instruments are fit for the circumstances we face at the moment."
He told the Commons: "It would be a profound mistake to pull out of these instruments, because the first thing that would follow is every other country in the world that adheres to these instruments would pull out of all their agreements with this country.
"That would be catastrophic for dealing with the problem that we are dealing with."
Mrs Mahmood added "if people who support this instrument and want it to work can't have this debate in a sensible way, then I mean honestly there's no hope really at all, for anybody."
Ms Mahmood said the Government was "not wanting to play, as you might say, populist politics with it".
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