The leading pro-North Korea association in Japan is losing strength as its membership has dwindled to about 40-thousand.

Voice of America reported on the decline of Chongryeon, citing Japanese government efforts to suppress the group. The U.S. government-funded broadcaster also noted that in 1955, about 500-thousand of the 600-thousand ethnic Koreans in Japan were pro-Pyongyang.

It said, however, that many of the group's members with North Korean citizenship have since become South Korean nationals. The report also attributed the organization's decline to losses in the slot machine industry, a major source of income for ethnic Koreans in Japan.