Seoul, July 12 -- South Korea said Friday it wants an investigation by the United Nations or another international body as it continues to reject Japanese claims that Seoul could not be trusted to faithfully implement sanctions against North Korea.

Kim You-geun, deputy director of South Korea's presidential national security office, said South Korea has been thoroughly implementing U.N. sanctions against North Korea over its nuclear weapons program. He demanded that Japan provide evidence for claims made by Prime Minister Shinzo Abe and his conservative aides that there may have been illegal transfers of sensitive materials from South Korea to North Korea.

Tokyo last week tightened the approval process for Japanese shipments of photores...