An estimated 250m children are employed worldwide
Child labour is the focus of an international conference beginning in the Netherlands.
An estimated 250 million children aged between five and 15 are employed worldwide, mostly in developing countries.
In Africa one in three children have jobs, and a further 10 million children work in slavery in South East Asia.
The three-day conference will mainly focus on one of the worst forms of child labour, work which is hazardous and puts children at risk.
Many children work in very bad conditions, without employment contracts, social insurance or holidays.
The 300 experts from 50 countries taking part in the conference aim to come up with a definition of the term "hazardous work".
This implies working under harsh and dangerous circumstances, likely to harm children's health, safety or morals - such as jobs in mining or construction, and the recruitment of children in armed conflict.
The International Labour Organisation is about to implement a 1999 convention abolishing hazardous child labour, but governments need firstly to agree on what types of jobs can be categorised as hazardous.
The convention, ratified by a 116 countries, will also ban compulsory child labour, the trafficking of children, and exploiting them for elicit activities such as drug smuggling and prostitution.
Governments and civil society groups attending the conference will form alliances aimed at phasing out child labour, and at supporting labour inspectors, particularly in countries where the worst forms of child labour are widespread.