Relatives of Japanese people abducted by North Korea in the 1970s and 1980s said Monday that the summit between the leaders of the United States and North Korea in Singapore presents a now-or-never opportunity for the return of their loved ones.

"This will be the only chance. We will be counting on President Trump's ability (as a deal maker)," said Shigeo Iizuka, the 80-year-old head of a group representing abductees' families, ahead of the summit Tuesday between U.S. President Donald Trump and North Korean leader Kim Jong Un.

(Supplied photo shows Trump meeting with relatives of Japanese nationals abducted by North Korea in Tokyo on Nov. 6, 2017)

Iizuka's younger sister Yaeko Taguchi was abducted by North Korea when she was 22 years old.

"Please return our children in good shape. We would like to make sure this message will be conveyed (to Kim)," said Sakie Yokota, 82, whose daughter Megumi was kidnapped at age 13 on her way home from school in Niigata Prefecture in 1977.

The teen's abduction has become symbolic of the issue, and Trump spoke about her during his address at the U.N. General Assembly in September.

Looking back at her long battle to secure the return of her daughter, Yokota said, "I hope Mr. Kim Jong Un will understand the feelings of the parents."

Japanese Prime Minister Shinzo Abe said Trump reaffirmed during a phone call Monday that he will push for the resolution of the abduction issue during the summit, following his pledge during a meeting with Abe in Washington last week.

(Sakie Yokota visits an exhibition of photographs of her daughter in Tokyo on May 8)

Yokota said she wondered how Japan would be viewed by the rest of the world if it cannot seize such a golden opportunity, expressing her hope for the realization of a meeting between Abe and Kim as well as enhanced efforts by the Japanese government toward resolving the abduction issue.

Iizuka spoke highly of Trump's promise to include the abduction issue in the summit agenda along with the denuclearization of North Korea, hoping the return of the abductees will be ensured at the U.S.-North Korean summit before actual procedures for the return are worked out between Japan and North Korea.

"If we fail to capitalize on this opportunity, the abduction issue will vanish," he said.

Japan officially lists 17 citizens as abduction victims and suspects North Korea's involvement in many more disappearances. While five of the 17 were repatriated in 2002, Pyongyang maintains that eight -- including Megumi Yokota -- have died and the other four never entered the country.