Police from London have gone to Romania to try to persuade people not to come to Britain without jobs.
Officers visited impoverished parts of the eastern European country, warning residents they were at risk of being victims of crime or becoming criminals themselves.
It included a trip to a village that almost all of a group of 68 Romanians evicted from a football club in North London had been traced back to.
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Chief Superintendent Adrian Usher, whose Barnet patch has a large number of Romanians living there, told the BBC's Panorama: "If you come to the UK without a named job to come to, you are at increased risk of being exploited or of being the victim or the perpetuator of crime."
Usher refused to be drawn on the political row over Romanian immigration, ahead of the lifting of visa restrictions on January 1.
Ukip, which has claimed huge numbers of migrants will arrive in Britain, was not impressed.
Deputy leader Paul Nuttall branded the police's tactics a “sorry state of affairs”.
It came as a split emerged between Nick Clegg and Theresa May over the issue.
May, the Home Secretary, is reportedly looking into limiting the scale of EU immigration.
But Lib Dem leader Clegg dismissed this idea as "illegal and undeliverable".