South Korea paid tribute to wartime Korean forced laborers at Japan’s Sado Island Gold Mines in a memorial ceremony on Monday, a day after boycotting a similar event organized by Japan, as tensions over historical atrocities continue to impact relations between the two sides.

SEOUL (Reuters) - South Korea expressed regret to Japan on Monday over Tokyo's attitude towards a memorial service held for labourers including Koreans forced to work in Japan's Sado mines during World War Two, Seoul's foreign ministry said.

After boycotting one organised by Tokyo, South Korea held its own memorial event on Monday for compatriots forced to work in a Japanese mine during World War Two, highlighting lingering sensitivities between the countries.

South Korea’s government says it has decided not to attend a memorial service near Japan’s Sado Island Gold Mines due to unspecified disagreements with Japan over the event, which stirred longstanding tensions over the abuse of Korean forced laborers at the site before the end of World War II.

North Korea condemned on Saturday recent joint military drills by the United States, South Korea and Japan, warning that it would take immediate actions if needed to defend the state.

South Korea’s decision not to participate in what was envisioned an a moment of reconciliation highlighted the perceived lack of sincerity in Japan’s treatment of historical issues.