Exceptions would only apply to migrants at risk of 'irreversible harm'

Illegal immigrants would be put on a plane before they get the chance to appeal under Conservative plans to rip up deportation laws.

Home Secretary Theresa May wants to implement a new regime of 'deport first, appeal later'.

The rules, to be brought in if the Tories are re-elected, would apply to anyone with an expired visa or those living in Britain without permission.

The only exceptions would be asylum-seekers or migrants who could suffer 'irreversible' harm if sent back to a dangerous country. The move seeks to end the racket of thousands of illegal immigrants being able to prolong their stay in Britain for months or even years by lodging a string of appeals and judicial reviews.

The only exemptions to the new rules would be asylum seekers or migrants who could suffer 'irreversible harm' if sent back to their home country. File image used

Officials also hope the crackdown – central to Tory manifesto plans to slash net migration – will save the taxpayer money.

Migrants will still be able to appeal – but must do so from their country of origin. It is thought that fewer people will then attempt to play the system, sparing the UK taxpayer the cost of holding them in an immigration centre or paying for housing.

The Conservative manifesto is yet to be completed and has undergone a series of re-writes in recent weeks.

But senior Government sources say it will once again contain a target to slash net migration – with renewed focus on removing more people from the country as a way of achieving it.

Mrs May is pressing for a firm restatement of the Prime Minister's 'tens of thousands' target – despite the fact it was missed spectacularly.

David Cameron remains committed to slashing net migration – the number of people arriving in the country against those leaving – which currently stands at 298,000.

By increasing the number of illegal immigrants who are removed from the country, it makes it easier to hit the target. Until now, the focus has been primarily on reducing the numbers coming in.

Home Secretary Theresa May wants to implement a new regime of 'deport first, appeal later' should the Tories gain re-election

Mrs May, hinting at the plans earlier this month, said: 'I think we will keep the target. It is important because it is about not just dealing with those coming into the system, but also about making sure that those people who shouldn't live here actually leave.' Tory insiders are satisfied the so–called 'non-suspensive appeals' policy is legally water-tight and will not be derailed by Labour's Human Rights Act.

On a smaller scale, Mrs May has for the past year been deporting foreign criminals under an identical 'deport first, appeal later' regime. So far the move has seen 600 offenders sent home before their appeals were exhausted.

Deportees and their lawyers lodged a series of judicial reviews against the scheme in the hope it would be ruled unlawful. But in a string of test cases, judges found there was no barrier to making foreign offenders lodge their claims from their home countries.

Those kicked out so far include a Nigerian woman who claimed to have a human right to a family life in the UK – despite being convicted of repeatedly beating her own child. Under the old system she could have delayed her case for years by lodging a string of appeals in the British courts.

With an estimated one million illegal immigrants living in the UK, the Home Office has a large group to target. But campaign groups have raised concerns that the department lacks the resources to track them all down.

MigrationWatch said the £1.8billion Britain spends securing borders and removing illegal immigrants and foreign criminals was 'clearly inadequate' – and six times less than the estimated £12billion overseas aid budget. While the number of migrants arriving in the UK has increased sharply in recent years, the number being removed has stayed flat at around 100,000 every year.

The Mail understands Mr Cameron is considering including two different targets in the final manifesto. In addition to the 'tens of thousands' target, he could also opt for a specific pledge to slash net migration from outside the EU – which, unlike EU migration, ministers can fully control.