A civic group holds a rally near the presidential office in Seoul, Nov. 26, denouncing Japan's memorial ceremony for forced labor victims from the Sado mine complex. Yonhap

Korea has expressed regret to Japan over the way Tokyo has handled the memorial ceremony for the wartime forced labor victims, including Koreans, from an old Japanese mine complex during World War II, Seoul's foreign ministry said Tuesday.

Seoul delivered its position to Tokyo on Monday, a day after it boycotted the Japan-hosted memorial event held near the mine site due to what it described as Tokyo's lack of efforts in commemorating the victims in a sincere manner.

"We expressed regret over Japan's attitude in the course of our negotiations over the memorial ceremony," the ministry said in a message to reporters.

The complaint was said to have been delivered through some form of "contact" with the Japanese side, according to a source, suggesting that no summoning of a Japanese embassy official took place.

Second Vice Foreign Minister Kang In-sun said by choosing not to participate in the ceremony, the government sent a clear message of disapproval to Japan about the memorial event.

"The decision was a strong protest by our government to Japan that the memorial service fell short of the standards for what was originally agreed upon between Korea and Japan," Kang said in a media briefing.

"The decision is, in itself, us expressing our strong regret," Kang said.

Holding such an event was part of a condition Japan had agreed to for Seoul's consent for the site's inscription as a UNESCO World Heritage site in July.

Korea had requested Japan hold a memorial ceremony for the victims every year in a way that reflects the "full history" of the mine complex, where many Koreans were forcibly taken to toil under Japan's 1910-1945 colonial rule.

It also requested a vice minister-level Japanese official attend this year's event.

Korea announced Saturday, just a day before the event, that it would not attend the memorial, citing disagreements with Japan over issues that it said were unable to be resolved.

Seoul's foreign ministry said the decision was made to express the government's "firm determination" that it will not compromise on historical issues.

Seoul officials held a separate memorial event Sunday with the victim's family members near the mine site, on Sado Island, off Japan's west coast.

"The foreign ministry finds it fortunate that we were able to provide a meaningful time to the bereaved families to honor the victims through our own memorial ceremony," Kang said.

"We will continue close communication with Japan to ensure that this issue does not escalate into an unnecessary conflict and can be managed as an individual matter," she said. (Yonhap)