Sakie Yokota, whose daughter Megumi remains missing after her abduction at the age of 13 by North Korean agents in 1977, has expressed her frustration with the Japanese government 20 years after a historic bilateral summit that saw the return of other abductees.

Tokyo officially lists 17 Japanese nationals as having been abducted by North Korea in the 1970s and 1980s. Five of them were returned after then-Prime Minister Junichiro Koizumi met with North Korea's Kim Jong Il in Pyongyang on Sept. 17, 2002, the first-ever summit between the two countries in the absence of diplomatic ties.

The five returnees were Yasushi Chimura, his wife Fukie, Kaoru Hasuike, his wife Yukiko and Hitomi Soga. Of the remaining 12, North Korea claims eight, including Megumi, have already died and four never entered the country, a claim rejected by Japan.