A network of mines on a Japanese island infamous for using conscripted wartime labour was added to Unesco's World Heritage register on Saturday after South Korea dropped earlier objections to its listing.

The Sado gold and silver mines, now a popular tourist attraction, are believed to have started operating as early as the 12th century and produced until after World War II.

Japan had put a case for World Heritage listing because of their lengthy history and the artisanal mining techniques used there at a time when European mines had turned to mechanisation.

The proposal was opposed by Seoul when it was first put because of the use of involuntary Korean labour during World War II, when Japan occupied the Korean peninsula.

But South Korea's foreign ministry said it had agreed to the listing "on the condition that Japan faithfully implements the recommendation... to reflect the 'full history' at the Sado Gold Mine site."

Unesco confirmed the listing at its ongoing committee meeting in New Delhi after a bid highlighting the archaeological preservation of "mining activities and social and labour organisation."

"The inscription was the result of a 14-year effort," Japanese Prime Minister Fumio Kishida said on X.

"I would like to share this joy with local people as well as all Japanese citizens."

Japan had reiterated a pledge to keeping the memories alive of "the harsh labour conditions of all workers," the foreign ministry in Tokyo said in a statement.

It added that exhibits on Sado island included data showing a higher percentage of Korean labourers were engaged in dangerous underground tasks, while others fled or were detained.

Historians have argued that recruitment conditions at the mine effectively amounted to forced labour, and that Korean workers faced significantly harsher conditions than their Japanese counterparts.

"Discrimination did exist," Toyomi Asano, a professor of history of Japanese politics at Tokyo's Waseda University, said in 2022.

"Their working conditions were very bad and dangerous. The most dangerous jobs were allocated to them."

The Sado mines were listed alongside the Beijing Central Axis, a collection of former imperial palaces and gardens in the Chinese capital.

The 589-hectare heritage area reflects "the ancient Chinese tradition of urban planning, serving as an important emblem that highlights the distinctive characteristics of Chinese civilisation," state news agency Xinhua said.

Other listings this week include the centuries-old, ornate burial mounds of the Ahom Dynasty in northeastern India and the Marquesas Islands in French Polynesia.

The Saint Hilarion complex, one of the oldest monasteries in the Middle East dating back to the fourth century, was meanwhile added to a list of World Heritage sites in danger due to the war in Gaza.

The Unesco committee meeting runs until Wednesday. (AFP)