There is concern that the number of migrant workers sleeping rough in part of Lincolnshire is increasing.
The number of foreign visitors to a Boston centre's "drop in" sessions doubled during June.
Centrepoint Outreach said figures for July are expected to show another substantial rise.
Staff at the centre said some people who come to the country to work are promised jobs and wages which do not materialise.
John Marshall, head of the centre, said: "People from EU countries have a perfect right to live and work here, it's just that they have been made promises in their own countries, perhaps responding to adverts.
"One man recently told us he saw an advert that said 'Come to Lincolnshire' and told him work was available and he could earn £2,000 in a month - which is totally unrealistic."