Guests offer a moment of silence during a memorial ceremony for the Sado Island Gold Mine in Sado, Niigata prefecture, Japan, as several seats reserved for South Korean guests remained empty Sunday. AP

South Korea's decision to skip a memorial ceremony hosted by Japan on Sunday reflects its "strong protest and regret" over Tokyo proceeding with the event in a way that fell short of the standards it had publicly pledged to uphold, Second Vice Foreign Minister Kang In-sun said Tuesday.

Kang, however, sidestepped criticism of the South Korean Foreign Ministry’s failure to coordinate effectively with Japan on the ceremony, which Seoul had envisioned as an occasion to genuinely honor the Korean victims of forced labor at gold mines on Sado Island during Japan's 1910-45 colonial rule of Korea.

Speaking at a press briefing, Kang explained that the Foreign Ministry in Seoul had no option but to make a last-minute decision to boycott Japan's memorial as it could not accept the final plan proposed by the Japanese authorities, despite close communication between the two governments.

Seoul viewed Japan's final proposal as falling short of the standards agreed upon in July when Tokyo sought Seoul's consent for the inscription of the Sado Island Gold Mines on the UNESCO World Heritage List, despite its history of forcibly mobilizing Korean workers, according to Kang.

"Our decision not to attend the memorial ceremony hosted by Japan was a strong protest by our government against Japan holding a ceremony that fell short of the level initially agreed upon between the two sides, and in itself was an expression of strong regret," Kang told reporters.

During July's UNESCO session, the Japanese delegation pledged to honor its commitments, emphasizing “sincerely remembering all the workers at the Sado Island Gold Mines, especially those from the Korean Peninsula,” and vowed to hold a memorial event for all the workers annually at the site.

However, in her remarks at the event, Japanese government representative and Parliamentary Vice-Minister for Foreign Affairs Akiko Ikuina neither addressed the forced mobilization of Korean workers nor offered an apology.

Kang also said that on Monday, a South Korean Foreign Ministry official contacted the Japanese Embassy in Seoul to "express regret over Japan's attitude during consultations between the two countries regarding the memorial ceremony," without providing further details.

This marks the first time a high-level Foreign Ministry official has conveyed the South Korean government's protest and regret over Japan's memorial ceremony, amid repeated expressions of regret by the Japanese government regarding South Korea's boycott.

However, Kang, who oversaw the South Korean Foreign Ministry's coordination with the Japanese authorities regarding Sunday’s memorial ceremony, did not apologize or acknowledge of any shortcomings on the part of the ministry.

After failing to reconcile differences with Japan, South Korea's Foreign Ministry held its own memorial ceremony on Monday at Sado Island to honor the Korean workers at the Sado Island Gold Mines, attended by relatives of the deceased victims of forced labor.

Kang reiterated the Yoon Suk Yeol government's position of "advancing bilateral relations in a manner that aligns with the interests of both countries, based on the principle of not compromising with Japan on historical issues."

"Furthermore, we will continue to communicate closely with Japan to ensure that the matter of the memorial ceremony is managed as a separate issue and does not affect the broader South Korea-Japan relationship," Kang said.