Japan will become a party to a global treaty on child custody as early as next year amid growing calls abroad for Tokyo to join it and help resolve custody problems resulting from failed international marriages, government sources said Saturday.

The government will develop domestic laws in line with the Hague Convention on the Civil Aspects of International Child Abduction, which provides a procedure for the prompt return of "abducted" children to their habitual country of residence and protects parental access rights, the sources said.

Complaints have been growing over cases in which a Japanese parent, often a mother, brings an offspring to Japan without the consent of the foreign parent, or regardless of custody determination in other countries, and denies the other parent access to the child.