Image copyright EPA Image caption Kim Seong-ju (C) was among the victims and relatives celebrating the victory in Seoul

South Korea's top court has ordered a Japanese firm to compensate Koreans it used as forced labour in World War Two.

Mitsubishi Heavy Industries Limited has been ordered to pay up to 150m won ($133,000; £104,000) to 28 South Korean victims or their families.

The court's ruling upholds two separate damages suits against the firm.

About 150,000 Koreans were conscripted to work in factories and mines in Japan in the war, and issues from the era continue to sour diplomatic relations.

The latest move follows a landmark case in October that found in favour of Koreans seeking compensation from Japan's Nippon Steel and Sumitomo Metal Corp for wartime forced labour.

Mitsubishi Heavy said the court's ruling was "deeply regrettable", and that it would take appropriate measures, Reuters reported.

'Regrettable and unacceptable'

Japan argues that all financial or other reparation issues related to their 1910 to 1945 rule of Korea should be regarded as settled by a treaty signed between South Korea and Japan in 1965.

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But the court ruled that the treaty "does not cover the right of the victims of forced labour to compensation for crimes against humanity committed by a Japanese company in direct connection with the Japanese government's illegal colonial rule and war of aggression against the Korean peninsula".

Japan's Foreign Minister Taro Kono said the ruling was "very regrettable and unacceptable".

He said it was in violation of international law and warned that Japan would consider options including an international law suit unless Seoul took appropriate action to address the issue.

Officials in Seoul however have said they respect the Supreme Court verdict, Yonhap news agency reported.

What will Mitsubishi pay?

The plaintiffs had sued Mitsubishi in Japan, but in 2008 Japan's top court found in favour of the firm.

Thursday's ruling ordered the company to pay up to 150m won ($106,896; £83,305) each to four women, and one family member, who said they had been forced to work without pay at a Mitsubishi aircraft plant in Nagoya in 1944.

One of the plaintiffs, 90-year-old Kim Seong-ju, cried as she spoke to the press on Thursday.

"I have harboured this grudge for all my life, and I'm still living as if all my bones protrude. That's the weight of my grudges," she said, as reported by Yonhap.

The second case initially involved six victims, but just two are still alive. Mitsubishi must now pay 80m won to the living victims and the same to be divided among the families of the deceased.