Until 2003, the Committee of the Convention of the Rights of the Child (CRC) tended to refer to foreign children in general without singling out migrant children. Since then, it has started to clarify the status of foreign children: whether they are migrant children, children of migrant workers, regular or irregular, refugee children or asylum seekers, or children under special protection measures. Since 2000, the Committee of the CRC has also developed a strong interest in trafficking, including the situation of trafficked children once returned to their country of origin. This is notably due to the adoption in 2000 and entry into force in 2002 of the Optional Protocol on the Sale of Children. The main concern of the Committee is discrimination in access to adequate social services, in particular health and education facilities for migrant children in general and irregular migrant children in particular. Another concern is the issue of birth registration for irregular migrant children and children born of foreign parents. The Committee also examines child labour and economic exploitation and recommends that the best interest of the child be taken into account. It also expresses concern over the situation of migrant children in detention and immigrant reception centres (ICMC and December 18 2007).