Park Chan-dae, floor leader of the main opposition Democratic Party, speaks during the party's Supreme Council meeting on Monday. (Yonhap)

The main opposition Democratic Party on Monday criticized the government for failing to prevent a Japanese gold mine associated with Korea's wartime forced labor from being listed as a UNESCO World Heritage Site.

On Saturday, the UNESCO World Heritage committee decided to add the controversial mine as a cultural heritage site after South Korea, which had initially opposed Tokyo's bid, gave last-minute consent to the listing.

"The Sado mine was listed as World Heritage, backed by the praise of the Yoon Suk Yeol administration," DP floor leader Park Chan-dae said during a Supreme Council meeting. "This move, which endorses Japan's distortion of its war crimes, makes it hard to tell whether our government is the Korean government or a government under Japan's colonial rule."

He vowed to conduct an investigation to hold those accountable for what he called a diplomatic "disaster."

An estimated 2,000 Koreans were forcibly mobilized to work under harsh conditions at the Sado mine during World War II, when Korea was under Japan's 1910-45 colonial rule.

Earlier this month, the International Council on Monuments and Sites recommended referring the nomination of the Sado mine back to Japan, calling for a more comprehensive explanation of its entire history. In its original submission, Japan limited the mine's timeline to the Edo period (1603-1868), excluding the modern history during which war atrocities were committed.

South Korea had initially protested Tokyo's push to enlist the mine but later agreed to the inscription on the condition that Japan faithfully carries out recommendations by ICOMOS and takes measures to portray the entire history of the mine, including its dark side.

To demonstrate its commitment, Japan has installed new exhibits at the Sado mine site to commemorate the harsh working conditions and decided to hold annual memorial services for the mine workers. (Yonhap)