Japan should take a "more humble" attitude towards the past, South Korean President Moon Jae-in said on Thursday, with relations between the two US allies and capitalist democracies long strained by disputes over history and territory.

The issues largely stem from Japan's brutal 1910-1945 colonial rule over the Korean peninsula and Moon told reporters: "I think the Japanese government should take a more humble attitude... but the Japanese politicians are politicising the issue."

Current arguments largely centre on the so-called "comfort women" pressed into sexual slavery for Japanese troops during World War II and labourers made to work for Japanese firms, with a territorial dispute also rumbling over islands controlled by Seoul.

A South Korean court last week authorised the seizure of assets belonging to Nippon Steel & Sumitomo Metal, after the Japanese firm failed to comply with an earlier order to compensate victims of forced labour.

Tokyo on Wednesday called the court decision "extremely regrettable" and summoned the South Korean ambassador to protest.

According to official Seoul data, as well as the comfort women, around 780 000 Koreans were conscripted into forced labour by Japan during its 35-year occupation.

Japan maintains that all historical compensation issues between the two nations were settled under the 1965 treaty that re-established diplomatic relations between them.

Under the treaty, a package of about $800m in grants and cheap loans was provided to the former colony in compensation.

Tokyo argues the court decisions are a breach of the treaty and international law.

Moon said many South Koreans felt the 1965 treaty did not solve all issues for the victims, adding such views were "not created by the government but by unfortunate history" and telling reporters: "We should respect the court ruling."