TOKYO (AP) _ Japan became the first country in a decade Friday to legally import ivory, unloading 50 tons of elephant tusks from southern Africa at a Tokyo harbor under U.N. supervision.

International trade in ivory was banned in 1989, but the United Nations authorized an experimental sale of elephant tusks from Namibia, Zimbabwe and Botswana to Japan after an explosion in the elephant populations of those southern African countries.

The sale was authorized in 1997 on condition the tusks be harvested from elephants that died naturally or were killed for population control. All proceeds of the sale must go toward elephant conservation.

``We are completely satisfied that all of the conditions were met,'' said Mario Hernandez, a member of the U.N. team that supervised the unloading.

Ivory has long played an important role in Japanese life and art. It is used in everything from name-seals employed instead of signatures in official documents to traditional figurines and picks for ``shamisen'' lutes.

``This experimental trade ... will contribute to the conservation of elephants as well as to the maintenance of Japanese culture,'' said Kageo Takaichi, chairman of the Japan Ivory Association.

Environmental groups are concerned that the U.N.-sanctioned trade will lead to an upsurge in elephant hunting.

The sale ``must not lead to an increase in illicit elephant hunts,'' the World Wildlife Fund said. ``We will continue to monitor the traffic of ivory.''

The price-tag on the ivory will be kept secret until the fall under the terms of the agreement between Japan and the African countries.