Sex workers from Poland (4%), Hungary (4%) and Latvia, Lithuania, Estonia, Slovakia and the Czech Republic (on 3% each) are also a growing part of the sector.

The figures stand in contrast to 2006 when Russia and Ukraine topped the league table.

Prostitutes from Nigeria, Brazil, Belarus and Thailand continue to feature prominently in the survey then as now, however.

"The most significant factor [behind the changes] seems to be the enlargement of the EU, as people from the new EU countries no longer require visas to be able to travel within its borders, while stricter conditions for getting visas apply to non-EU citizens," the Tampep report says.

"The extremely high level of migration flow from central and eastern Europe, almost 70 percent, is testament to the great economic and social inequalities that prompt this movement."

Focusing in on some of the figures, the Tampep survey found that impoverished ethnic minorities often do the most dangerous kind of work: In Romania, more than half of all street prostitutes are Roma. In the Baltic states, the same is true of ethnic Russians.

The Tampep report shows striking differences in the EU sex industry across the east/west divide.

In most western countries, such as Denmark (65%), Finland (69%), Germany (65%), Greece (73%), Italy (90%), Spain (90%), Austria (78%), Belgium (60%), France (61%) and the Netherlands (60%), the vast majority of prostitutes are migrants.

But in former Communist countries the reverse is true, with, for example 98 percent of sex workers in Slovakia, Romania and Bulgaria, 90 percent in Lithuania and 66 percent in Poland being of national origin.

In some western countries, the change in demographic in the years following EU enlargement is startling.

Denmark went from 50 percent migrant workers to 65 percent in the past few years. Italy went from 80 percent to 90 percent and Spain jumped from 70 percent to 90 percent.