TOKYO - The United States and three other western nations Thursday urged Japan to sign an accord against parental child abductions, saying scores of children are being held in the country.

US, French, British and Canadian diplomats launched the rare joint appeal at a US embassy press conference, listing cases of foreign parents who have been unable to see their children in Japan after a breakup or divorce.

"We do feel a sense of urgency because the number of cases is increasing very dramatically," said acting US ambassador to Japan James Zumwalt.

"I think because we have more and more international marriages, we can expect in the future a further increase in the number of these cases." The United States had received reports of 73 cases of parental abductions involving 104 children in Japan, said Michele Bond, the US State Department's deputy assistant secretary for overseas citizen services.

In 29 more cases, all family members were in Japan, but the US parent was denied access to a child after a separation or divorce, she said.

Britain, France and Canada between them reported 95 similar cases. In one case a French father "has no contact whatsoever, never ever, with his daughter," said Christophe Penot, French deputy head of mission.

"It's almost unbearable for a human being to find himself in such a situation." Japan is the only Group of Seven member country that has not signed the 1980 Hague Convention on the Civil Aspects of International Child Abduction.

The Hague treaty requires a country to expeditiously return abducted children to their country of habitual residence. However, even if Japan signed the treaty, it would still have to change its civil law so that it applied.

 In contrast to other developed nations, visitation rights are not enshrined in Japanese law and child abduction by one parent is not a crime. Every year in Japan, following a break-up or divorce, 166,000 children are separated, usually definitively, from one of their parents - the father in 80 percent of cases - according to official statistics.

Eighteen Japanese associations of parents deprived of their children are fighting, alongside Japanese lawmakers, for reform of the system.

Bond said some Japanese parents were also affected in international cases. "There are many cases of Japanese citizens' children who have been abducted to other countries - to our own countries or to other countries," she said.

"Because Japan is not a member of the Hague Convention, even if the children are abducted to a Hague convention member state, Japan cannot benefit from that because it's not a Hague partner," she added.

Bond said she had met officials of Japan's foreign and justice ministries who had reiterated that "the government is very seriously and carefully considering accession to the Hague Convention," she said.

"We do wish to urge the government of Japan to proceed with greater speed perhaps, because it is an issue which has been under serious and careful consideration for quite some time," she said.