President Reagan signed legislation Friday designed to make it easier for parents to recover children who have been wrongfully abducted across international borders in domestic custody disputes.

The measure implements the 1980 Hague Convention on the Civil Aspects of International Child Abduction, to which the United States is a party. The convention creates a treaty obligation for the prompt return of such children.The convention was written to cover instances such as one in which an American marries a German while stationed in West Germany with the armed forces, they have a child and settle in the United States, and the German partner then returns to Germany with the child.

Supporters of the measure said current law provides no way to assure speedy determination of custody rights in such a situation.

The administration supported the bill, although the Justice Department objected to one provision giving federal and state courts concurrent jurisdiction to hear cases brought under the convention. The department contended that federal courts never have been, and should not be, involved in custody matters.