TOKYO (AP) — Bones, likely to be human, have been recovered at a wartime undersea mine in western Japan where about 180 mostly Korean forced laborers died in an accident in 1942, according to a Japanese civil group helping in the search for their remains.

Three possible limb bones and a skull were found in the past two days by Korean divers at the former site of the Chosei Mine in Yamaguchi prefecture, according the group known as Kizamu Kai.

The bones were to be examined by local police to determine whether they belong to any of the victims who died at the mine 83 years ago.

If confirmed, the discovery is expected to accelerate efforts to recover other remains of the 136 Korean forced laborers and 47 Japanese workers killed in the mine collapse.

“I was waiting for this day,” group representative Yoko Inoue said.

The recovery of the possible human bones comes just days after a weekend summit in Tokyo between Prime Minister Shigeru Ishiba and South Korean President Lee Jae Myung showcasing friendly ties between the two countries to cooperate on major challenges, such as regional security and trade, while avoiding historical differences.

The Chosei undersea mine started operations in 1914. In February 1942, part of the ceiling of a mine shaft collapsed, flooding the mine and killing the 183 workers inside. The accident had long been forgotten until a group of citizens started to investigate in 1991, initially to erect a memorial for the victims and preserve the former mining site, including the entrance and a ventilation shaft.

Historians say Japan used hundreds of thousands of Korean laborers before and during World War II, including those forcibly brought from the Korean Peninsula, at Japanese mines and factories to make up for labor shortages because most working-age Japanese men had been sent to battlefronts across Asia and the Pacific.

Following years of work collecting witness accounts and historical documents about the mine, the group started undersea searches for the victims' remains last year.

Ishiba, who has acknowledged Japan’s wartime aggression and has shown more sympathy toward Asian victims, gave a nod earlier this year for his government to hear from experts on how searches can be carried out safely.

Chief Cabinet Secretary Yoshimasa Hayashi offered his condolences to all victims of the mine accident and said the government is following the police examination of the bones. He said the government has yet to obtain expertise on the safety of undersea searches for remains at the site.

Kizamu Kai has gone ahead with the searches at the mine site on its own. The Japanese health and welfare ministry, in charge of wartime remains, has been reluctant to help fund the searches.

Critics say Japan’s government has long been reticent to discuss wartime atrocities. That includes the sexual abuse and enslavement of Asian women — many of them Koreans known as “comfort women” — and Koreans mobilized and forced to work in Japan, especially in the final years of World War II.

Japan’s government has maintained that all wartime compensation issues between the two countries were resolved under the 1965 normalization treaty.

Korean compensation demands for Japan’s atrocities during its brutal colonial rule have repeatedly strained relations between the two Asian neighbors. But since 2023, their ties have improved under Washington's pressure to set aside differences that hamper crucial security cooperation as China's threat in the region grows.