Campaigners in Britain welcome Japan's plans to sign up for a treaty on settling cross-border child custody disputes but feel new procedures are needed to effectively implement the agreement.

Japan said in May it will join the 1980 Hague Convention on the Civil Aspects of International Child Abduction, which sets out rules for the prompt return of children under 16 to the country of their habitual residence in cases of international divorce.

"It's excellent Japan is going to sign up because there are lots of cases where children have been taken to Japan, often by their mothers, and the fathers can't get a return order," said Anne-Marie Hutcheson, a lawyer who specializes in this field.