Migrant register scheme to end
European law changes will, within weeks, allow thousands of migrants from the former Soviet bloc to claim a range of benefits and work in the UK without registering.
Restrictions imposed when eight eastern European states joined the EU in 2004 must be lifted at the start of May, allowing migrants to claim jobseeker's allowance, council tax benefit and housing benefit.
The end of the Workers Registration Scheme means migrants from the so-called A8 countries - the Czech Republic, Poland, Hungary, Slovakia, Slovenia, Estonia, Latvia and Lithuania - will no longer have to register if they wish to work for a month or more in Britain.
Estimates in The Times suggested that as many as 100,000 migrants could claim UK benefits running into tens of millions of pounds.
But the Department for Work and Pensions insisted that strict rules would remain in place to prevent abuse and stop "benefit tourism".
Immigration minister Damian Green pointed out that at the same time that the scheme ended in the UK, countries including Germany and Austria would open their labour markets to workers from their eastern neighbours.
Only Britain, Ireland and Sweden permitted free access to workers from A8 countries in 2004. It is thought that many will now be attracted to Germany and Austria, which are geographically nearer.
Mr Green said: "This Government will apply transitional controls for all new EU member states in accordance with the relevant Accession Treaty as a matter of course in the future.
"We are in the process of delivering major reform to bring immigration down to the tens of thousands with the introduction of a new limit on economic migrants from outside the EU, alongside new proposals to reform other routes of entry, including students, families and marriage."
The Department for Work and Pensions said it had no choice but to remain in line with national and international obligations. But the department insisted that protecting the benefit system from abuse was its "number one priority".