The government on Monday formally added Kyoko Matsumoto, who disappeared in Yonago, Tottori Prefecture, at age 29 in 1977, to the official list of Japanese abducted by North Korea.

Her inclusion brings the list to 17. Japan notified Pyongyang of the decision through the North Korean Embassy in Beijing, Chief Cabinet Secretary Yasuhisa Shiozaki said.

"We will strongly demand her immediate return to Japan and an inquiry," Shiozaki, acting on behalf of Prime Minister Shinzo Abe while he was away for the Asia-Pacific Economic Cooperation forum summit in Hanoi, told reporters.

Matsumoto's listing is not expected to lead to a breakthrough in resolving the abduction issue, which, along with Pyongyang's nuclear threat, has prevented the establishment of diplomatic relations.

Before Matsumoto's official inclusion, the government had listed 16 people as having been abducted by North Korea in 11 separate incidents in the 1970s and '80s. Five have been repatriated.

North Korea admitted in September 2002 to abducting 13 Japanese but claims that other than the five returnees are dead.

The process to officially list a missing person as an abductee to North Korea has taken a long time and been piecemeal, even though suspicions have been widespread for decades after dozens of people disappeared under mysterious circumstances. In Matsumoto's case, police first listed her as an abductee based on witness accounts.

It wasn't until January 2003 that the government for the first time officially declared it believed 15 Japanese had been abducted.

The actual number is considered to be far greater. It is possible that more than 100 Japanese were kidnapped, according to the National Association for the Rescue of Japanese Kidnapped by North Korea, a coalition of nonprofit organizations trying to learn the fate of the missing and bring them home.