Priti Patel is pushing for freedom of movement by European nationals into the UK to end on 31 October under a no-deal Brexit, it has been reported.
Both The Telegraph and The Independent report that the new home secretary wants border restrictions to be imposed immediately after Britain leaves the European Union if no agreement can be struck with the bloc.
The move would represent a major shift from the position of her predecessor, Sajid Javid, who had held back the government bill that would have brought free movement to an end amid fears of a Commons defeat.
But a Home Office source said: "Priti wants to toughen the Home Office's stance. She thinks Saj did a great job but with a new Prime Minister and new priorities changes needed to be made.
"For a start that means properly preparing for no deal, it's clear those in the centre had no intention of preparing for no deal."
Patel is said to believe that the immigration shake-up can be brought in through secondary legislation, a move that would allow her to effectively sideline MPs who might try to torpedo the Immigration and Social Security Co-Ordination Bill.
A source told The Telegraph that officials have been dispatched to Singapore to "understand how a well functioning immigration IT system is developed", including how to "count people in and out the country".
But Liberal Democrat home affairs spokesperson Sir Ed Davey said the proposal was “completely detached from reality and is next chapter in the never-ending saga of the utter mess they are making of Brexit.
"What would this mean for EU citizens who have made their home in the UK who have" travelled abroad when they try to return?"
The Lib Dem MP added: “Are the government seriously suggesting an NHS nurse who is an EU national may not be allowed to return to the country if they happen to have been on holiday? It is absurd."
Nicolas Hatton of the3million campaign group for EU citizens living in Britain meanwhile told The Independent: "There are no systems in place and nothing is ready. This is a political gesture, but it will have a real impact on people’s lives.
"This will open the door to discrimination. How will they distinguish between the ‘legacy people’, those already here, and those who will arrive afterwards?"