Nearly 20,000 people who arrived in the UK from outside Europe will be the first to be targeted in the new crackdown - to begin next month - which will force them to provide documentary proof of their immigration status.
The move comes months after a review by ministers established that, in total, 370,000 people who came to Britain as visitors, students or workers are now on work-related benefits. Foreign-born claimants is understood to make up 6.5 per cent of the total 5.5 people on benefits in the UK.
In January Chris Grayling, the employment minister, vowed: “We will root out those claimants who cannot prove their immigration status and in turn they will be stripped of their benefits.”
Whitehall documents seen by The Sunday Telegraph show in detail how ministers plan to deal with a “cohort” of “19,269 individuals with no readily identifiable immigration status.”
They continue: “DWP plans to start writing to these in two tranches, the first 10k on 3 September; the remainder on 1 October. Recipients are required within 28 days either with DWP or the UK Border Agency to establish their immigration status otherwise their benefits payments will be suspended.
“We did explore further sub-dividing the tranches, with a third later set in November, but this ran the risk of benefits being suspended just prior to Christmas.
“As well as building an immigration enforcement response to those identified as having no immigration status, the UK Border Agency will be providing support to DWP operational staff through verification of evidence of status.”
The documents go on to state the UKBA’s plans to deal with those with whom “no contact is made or where an immigration offender is identified.” They state: “As first order, we will identify those removable or high harm cases for tasking to the relevant LIT [local immigration team] for enforcement action.”
However, some will be identified as “not immediately removable,” the documents admit.
The letter to claimants thought to be abusing the system will state: “We are reviewing your entitlement to benefit and need to see evidence of your existing immigration status. You must ensure we receive your response within 28 days from the date of this letter or your benefit payments will be suspended.”
The crackdown may provoke opposition from the Liberal Democrats, who before the last general election proposed an amnesty for long-term illegal immigrants living in Britain, for being too harsh. The two parties’ differing stances on immigration are enshrined in the 2010 Coalition Agreement.
A DWP analysis of the initial 10,000-strong “tranche” of claimants who will receive letters next month showed that 57 per cent are women and 43 per cent men. More than a third (38 per cent) are aged between 35 and 44, while another 33 per cent are aged between 25 and 34. Some 17 per cent are aged between 45 and 54.
The most common benefit being claimed is Jobseekers Allowance (33 per cent). Some 36 per cent are claiming some form of lone parent allowance, while 16 per cent are on Employment Support Allowance or other incapacity benefit.
The new move comes after months in which ministers have faced attacks over their record on immigration. David Cameron has said his target is to bring net migration - the difference between those leaving the country and those coming here - below 100,000 by 2015. However, estimates suggest net migration will only drop to around 180,000 next year - leaving the Prime Minister highly unlikely to hit his target.
Ministers blame Labour for leaving behind a chaotic system which failed to record, among other things, the nationality of those claiming benefits. The Opposition, in turn, blames ministers’ “economic failures” for forcing more people on to benefits.