Of a total 9,500 cases reported in Europe, some 2,400 were in Italy, the NGO said in its 2013 report 'The Small Invisible Slaves', issued on the eve of the International Day for the Remembrance of the Slave Trade and its Abolition.
"It involves adults but also a large number of adolescents and children," said Raffaela Milano, Italy-Europe program director for Save the Children. Children from eastern Europe, Nigeria and Egypt ranked highest among groups most exploited as sex workers, beggars, or other types of illegal workers.
By Save the Children's estimate, there are 20.9 million victims of forced labor in the world.
The sector has not shown signs of slowing down amid the global economic crisis, the group said, with criminal and mafia organizations reaping billions of dollars often reinvested in weapons and drugs.
The trade only appears to be growing in Italy and the rest of Europe, Save the Children said.