Children who believe their human rights have been infringed can take their case to the United Nations under a new legal move.
The optional protocol to the Convention on the Rights of the Child has received the required 10th ratification from Costa Rica and will come into force on April 14.
Marta Santos Pais, the UN special representative on violence against children, said the "historic" move would place "the rights and aspirations of children at the centre of the human rights agenda" by giving youngsters the right to seek redress for abuses of their rights for the first time.
Initially, only children from Costa Rica and the nine other countries: Albania; Bolivia; Gabon; Germany; Montenegro; Portugal; Spain; Thailand; and Slovakia, will be able to submit complaints. But Ms Santos Pais said the UN and other organisations would keep promoting ratification of the protocol by the 183 other member states.
The Convention on the Rights of the Child, adopted by the UN General Assembly in 1989, ensures children of the right to a name, a nationality, an education, the highest possible standards of health, protection from abuse and exploitation, and the right to have their views heard.
Two previous optional protocols deal with children in armed conflict and the sale of children, child pornography and child prostitution.
Under the new agreement, children or their representatives will be able to submit complaints to the Committee on the Rights of the Child, which is composed of 18 independent human rights experts who monitor implementation of the convention and the two other optional protocols.
The committee will then decide whether to review the case. If a n abuse is found, it will recommend that the state concerned takes action to remedy the situation. It can also ask a state to take interim measures to protect a child or group of children or prevent any reprisals.
Committee chairwoman Kirsten Sandberg called the move "a major step forward in the implementation of children's rights".
"The optional protocol gives children who have exhausted all legal avenues in their own countries the possibility of applying to the committee," she said.
"It means children are able to fully exercise their rights and are empowered to have access to international human rights bodies in the same way adults are under several other human rights treaties."
She said the committee would have "child-sensitive procedures" and safeguards to ensure children were not being manipulated or used to make the complaint.
Ms Sandberg stressed that states had the primary responsibility to address child rights abuses and urged countries "to develop their own systems to ensure that children's rights are respected and protected and that their voices can be heard".