Robert Jenrick has called for the Home Office to be broken up, saying it is "incapable" of controlling immigration and securing the UK's borders.
Alongside former housing minister Neil O'Brien, the former immigration minister called for a new Department of Border Security and Immigration Control.
Its sole focus would be on migration policy.
They argued the rest of the responsibilities of the Home Office should be transferred over to a new Department for Policing and national Security.
Robert Jenrick has called for the Home Office to be broken up, saying it is "incapable" of controlling immigration and securing the UK's borders
PA
In a report for the Centre for Policy Studies published today, Jenrick and O'Brien said the changes would allow the Government to "instil a totally different culture in the Home Office", staffed with "new personnel and processes".
They said the Home Office had "fallen short" on immigration, despite it being an issue consistently at the top of voters' concerns.
While the duo said the department is staffed by "many good, hardworking people", it is "simply too unwieldy to function effectively", claiming it had been “undermined by high levels of churn and a lack of institutional knowledge”.
In their report, Jenrick and O’Brien argued that creating a separate department which solely focussed on immigration would ensure Britain has both a secretary of state and a bureaucracy “dedicated to delivering for the public on this vital issue”.
Jenrick, who quit as immigration minister in December, warned: “It would be unforgivable if the government did not use the time before the general election to undo the disastrous post-Brexit liberalisations that betrayed the express wishes of the British public for lower immigration.
“The changes we propose today would finally return numbers to the historical norm and deliver the highly-selective, highly-skilled immigration system voters were promised.
"These policies could be implemented immediately and would consign low-skilled mass migration to the past."
But the Home Office said it does not plan to break up the department.
The Government said: "The Prime Minister and Home Secretary have been clear that current levels of migration are far too high.
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"That is why the Government announced a plan to cut the number of migrants that would have come last year to the UK by 300,000 — the largest reduction ever.
"This plan is working, with the latest statistics showing applications across three major visa categories are down by 24 per cent.
"Our approach is fair — reducing immigration and ensuring businesses invest in and recruit from the domestic workforce, whilst prioritising the overseas workers and students who will contribute significantly to our economy."