There are now up to nine escort agencies advertising around Leitrim as a crackdown on the sex trade in Northern Ireland comes into force.
The number has “jumped” in the last month according to campaigners.
Laws making it a crime for anyone to pay for sex are now in force in Northern Ireland.
Brian Killoran, chief executive of the Immigrant Council of Ireland (ICI) said Border counties now face becoming a “safe haven” for sex traders in the absence of a similar ban here.
“Initial indications are that those who run prostitution have been feeling the heat of Northern Ireland’s new laws even before they came into force and have been switching their operations to the south,” he said.
Under the legislation, anyone caught paying for sex in Northern Ireland faces up to a year in prison and a fine of £1,000 sterling.
The ICI says profiles on escort agency websites linked to counties just over the border have soared in the four weeks leading up to the new law.
In Leitrim there are now nine escorts advertising their services at the end of May compared to two at the beginning of the month.