By Jack Kim SEOUL (Reuters) -After boycotting a memorial event organised by Tokyo, South Korea held its own on Monday to remember compatriots forced to work in a Japanese mine during World War Two, highlighting lingering sensitivities between the key U.

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.