The U.S., Canada and four other countries have jointly urged Japan to take legal steps to ensure that parents who have removed their children after the failure of international marriages will not be preferentially treated contrary to an international treaty on cross-border child custody disputes, government officials said Tuesday.

The six countries — including Britain, France, Australia and New Zealand — submitted the joint statement in writing, the officials said. It was part of the Justice and Foreign ministries' one-month public consultation from the end of September on interim proposals for domestic legislation prior to Japan's accession to the treaty.

The rare move reflects the countries' strong interest in Japan's accession to the Hague Convention on the Civil Aspects of International Child Abduction. The treaty is designed to ensure the prompt return of children who have been abducted from their country of habitual residence.

The envisioned domestic legislation would indicate that children will not have to be returned when the parent has fled an abusive spouse or could face criminal prosecution, presumably in connection with the abduction of offspring, in his or her country of habitual residence.

The joint opinion, submitted by the Canadian Embassy in Tokyo on behalf of the six governments, states that the interim proposals deviate from the convention, which allows the return of children to be rejected only when they could face a "grave risk" if returned, making spousal violence and other reasons inapplicable, the officials said.