There are still about 12.3 million people worldwide who work in some form of bonded or forced labour, according to a May 12 International Labour Organisation (ILO) report.
This includes 4.2 million sex workers and 8.1 million agricultural labourers, manufacturing workers and construction workers. Fifty-six percent of people in forced labour are female.
The report says seafarers, fishing boat crews and domestic workers are also high risk groups for forced labour.
According to ILO's The Cost of Coercion report, forced labourers earn approximately US$21 billion a year less than they would if they were properly paid.
The ILO warns this trend could become worse during the current economic downturn.
In April 2009, the ILO's Convention on Forced Labour was ratified by 173 of the ILO's 182 member countries, making it the most widely ratified of all ILO conventions. According to the report, a higher number of countries have outlawed forced labour and trafficking.
International Trade Union Confederation general secretary Guy Ryder welcomed the report saying: "The fact that forced labour still exists, and especially on such a huge scale, is an absolute scandal which the international community simply should not tolerate."