The government has drawn up a package of measures -- including the appointment of a special "G-man" task force -- to fulfill obligations under an international treaty that bans illicit traffic in cultural treasures, government sources said Thursday.

The package comes as the government is preparing to submit the 1970 UNESCO treaty to the current 150-day ordinary Diet session. Ratification would mark the country's first significant step toward shedding its notorious image as a safe haven for looters of cultural assets.

The sources said that the Agency for Cultural Affairs will appoint a team of experts to appraise, at customs authorities' request, foreign cultural assets that might have been stolen and illegally brought into Japan.

The task force will be appointed during the fiscal year that starts April 1 and will judge whether suspicious items are protected by the UNESCO treaty, the sources said.

The package of measures to comply with obligations under the UNESCO treaty also includes amendments to the Civil Code and the trade control ordinance, the sources said.

Under the current Civil Code, anyone who has acquired a stolen article, even legally without knowledge of any wrongdoing, must return it to the rightful owner, but only if the rightful owner files a court request within two years of losing the item, naming the current owner.

The Justice Ministry will revise the Civil Code to lengthen the window during which the proper owner of a stolen asset can ask for its return to five years.

The ministry will submit an amendment to the Civil Code to the current ordinary Diet session.

The sources also said that the Ministry of Economy, Trade and Industry will revise the trade control ordinance to oblige importers of cultural assets to obtain certificates from exporting countries to prove that items were not stolen or illegally taken out of the country.

The UNESCO Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property -- as the 1970 treaty is formally called -- was adopted to protect cultural assets against theft, illicit export and wrongful alienation. It took effect in 1972.

At present, Japan is among only a handful of industrialized countries that have yet to join the treaty. Britain is also not a treaty member.

Government officials and private-sector experts have often pointed out that Japan and Britain are notorious global centers of illegal trade in cultural assets, including those from such troubled countries as Afghanistan and Iraq.

Even Chief Cabinet Secretary Yasuo Fukuda acknowledged the problem on his Internet home page recently and stressed the need for Japan to join the 1970 UNESCO treaty, which bans illicit traffic in statues, paintings, manuscripts, books and other objects of historical or archaeological value, as soon as possible.

The UNESCO treaty obliges member countries to return inventoried properties that have been stolen from museums or similar institutions. In addition, the treaty requires member countries to take domestic measures to control the acquisition and illicit trading of cultural objects by individuals and institutions.