Asylum seekers who enter the UK from Europe face being rejected after Brexit under a shake-up planned by Priti Patel.
The Home Secretary is proposing legal changes that would mean asylum claims by migrants who come through the EU and enter the UK illegally will be deemed "inadmissible" once Britain leaves the EU at the end of this year.
The move follows a surge in migrants crossing the Channel on small boats and concern that the immigration and asylum system is "not fit for purpose", with lawful attempts to return applicants to other EU nations "frustrated by repeated legal claims" on human rights or other grounds.
The new legal post-Brexit framework would replace the Dublin Agreement under which the EU country through which an asylum seeker first enters the EU is judged responsible for examining their claim.
"If you come through the EU, an asylum claim would be inadmissible because you should have claimed it in the first country you entered," said a source.
Extending similar rules to migrants who have illegally entered the UK from non EU countries is also understood to be "on the table", although final decisions on the proposed shake-up have not been taken.
It comes as it emerged that migrants seeking asylum in Britain could be processed offshore under plans being developed by Ms Patel.
Officials have ruled out Ascension Island and St Helena as impractical because of their distance from the UK, but the Home Secretary is still considering options for a third country where asylum seekers could be held while their applications are processed.
Sources close to Ms Patel countered criticism of the proposal, which would require legislation, by citing similar plans by Tony Blair when he faced a surge in illegal migrants crossing the channel on lorries and ferries in 2003.
His transit processing centres in "protected zones in third countries" were designed to "deter those who enter the EU illegally and make unfounded asylum applications".
A Government source said: "We are looking at offshoring, but key will be finding an appropriate location."
Other options considered included Moldova, Morocco and Papua New Guinea. The Government is also considering converting disused ferries into centres moored off the coast where asylum applicants could be processed, according to The Times.
The measures are likely to form part of Ms Patel's proposed "Fair Borders Bill", which could be flagged as early as this Sunday when the Home Secretary delivers her keynote speech to the virtual Conservative conference.
The Bill is also expected to include plans to stop people drawing out the asylum application process by making them declare their grounds for refugee status when they apply, rather than being able to submit new reasons later.
Ms Patel reportedly told Tory MPs on a Zoom conference call six weeks ago that the asylum system was "broken" as she promised to introduce laws that would "send the left into meltdown".
She claimed the system was being "exploited by leftie Labour-supporting lawyers" doing everything they could to stop the Government removing people. Two weeks later, a deportation flight returning 23 illegal migrants to Spain was halted after last-minute legal actions by human rights lawyers.
Immigration minister Chris Philp signalled the changes when asked in the Commons whether the new Bill would "contain provisions that those who enter the UK illegally not being able to subsequently apply to stay in this country".
He said the asylum and immigration enforcement system was "not fit for purpose", adding: "We are often frustrated by repeated vexatious legal claims often at the last minute with the express intention of frustrating the proper application of the law.
"I can confirm we are working at pace on legislative options... and everything is on the table."
On Wednesday, Ms Patel criticised other EU nations for "endless legal barriers" that prevented the removal and return of asylum seekers even where the UK had fingerprint or other evidence that they should have or did apply for asylum first in other European countries.
"We have EU states themselves not following the European Union's Dublin Regulation and not taking back people who have been deemed to be found coming through those countries in the first place," she told the Blue Collar Conservatism Conference in Keighley.