Japan has expressed regret over South Korea’s decision not to attend a memorial event on Sunday to honor all the workers at the UNESCO World Heritage-registered Sado mines, including Koreans who were forced into hard labor at the mines during Japan’s colonial rule of the peninsula.

At a press conference on Monday, Chief Cabinet Secretary Yoshimasa Hayashi expressed his regrets but added that he was not in a position to explain the decision.

Hayashi’s remarks about Seoul’s absence are the first from a Japanese official.
   
Tokyo promised to hold an annual memorial ceremony for the Korean and Japanese laborers during UNESCO’s review of the World Heritage listing in July.

Seoul gave its consent to the listing on the condition that Tokyo take steps to inform international visitors about the full history of the site, including the annual memorial and an exhibit describing the harsh working conditions Koreans endured there.

The two sides, however, clashed while negotiating details of the event and who should participate.
   
South Korea held a separate memorial ceremony Monday morning on Sado Island in Niigata Prefecture.