North Korea's tourism bureau has, since around August, been asking a travel agency in Japan to sell commemorative stamps to Japanese people, according to public security authorities and sources well-versed in bilateral ties.

Likely behind the move is an effort by North Korea to make up for an apparent shortfall in hard currency at a time when the country has restricted trading with China, its main benefactor, due to the coronavirus pandemic.

The request involves asking the travel agency to seek out Japanese interested in North Korean postal stamps and sell them to such people. Among the targets are those who have traveled to North Korea before.

Authorities have been paying close attention to the move, particularly how the stamps can be brought into Japan and the money earned from the sale — in yen — can be remitted to North Korea.

Japan has in principle banned the import of goods from and the transfer of money to North Korea as part of sanctions imposed on the country over its nuclear and missile activities.

A sheet of stamps commemorating an air show held in Wonsan in the eastern part of North Korea in September 2016 can fetch ¥20,000 ($190), according to the sources.

There are also samples of stamps of commemorating a political gathering, which depict North Korean leader Kim Jong Un in the center, as well as those depicting a scene in which he stands close to Chinese President Xi Jinping during one of his visits to the neighboring country, the sources say.

The State General Bureau of Tourism made the request of a travel agency in Japan that handles trips to North Korea.

Amid the pandemic, North Korea is seeing a sharp fall in travelers from China and Southeast Asia.