South Korea expressed regret to Japan over memorial for mine workers

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.

South Korea boycotted a memorial held by Japan on Sunday and held its own the following day, saying the weekend event did not match up to what had been agreed by the nations.

A foreign ministry official sent a message of regret to the Japanese embassy in Seoul over Japan's attitude shown during the consultation process for the memorial, Seoul's foreign ministry said in a statement on Tuesday.

The official called for close communication to ensure the issue did not result in "unnecessary conflict," the ministry said.

The memorial has touched a nerve between Seoul and Tokyo which have seen ties generally improve in recent years, as they seek to put aside acrimonious disputes tied to Japan's 1910-45 colonisation of the Korean peninsula.

Japan's top government spokesperson, Yoshimasa Hayashi, said on Monday it was not Tokyo's place to explain South Korea's absence from the memorial ceremony held by Japan's government.

"But we do think it is regrettable that they did not participate," he told a daily briefing.