The Lower House on Thursday approved a bill needed to ratify an international treaty on settling cross-border child custody disputes, making it certain the Diet will enact it this summer following Upper House deliberations.

The 1980 Hague Convention on the Civil Aspects of International Child Abduction sets out the rules and procedures for promptly returning children under 16 who are taken or retained by one parent following the failure of an international marriage, to the country of their habitual residence if requested by the other parent.

Japan is the only Group of Eight nation yet to join the convention, which has 89 signatories. The G-8 comprises Britain, Canada, France, Germany, Italy, Japan, Russia and the United States.

The government of Prime Minister Shinzo Abe aims to join the convention early next year after completing all domestic procedures.

The bill that the Lower House unanimously approved stipulates the domestic process for returning such children to their habitual residence.