Rare footage of Korean women who were forced to work in brothels for the Japanese military during the Second World War has been released for the first time.

Known as "comfort women" they were used whenever the army invaded and occupied Asian countries from the early 1930s until the end of the war.

Until now, no footage of the women has ever been found, but Seoul National University brought together a team of researchers funded by the government, who found the material in the United States National Archives after two years of searching.

It is believed to have been filmed by an American soldier in 1944.

Seven barefooted women can be seen standing outside a brick house in then Japan-occupied China.

The 18-second clip shows Chinese soldiers questioning the women, in Southwestern Yunnan province.

The women in the video were found by US and Chinese allied forces. Two women depicted in the video previously appeared in photos released about comfort women.

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“South Korea has not had its own data on comfort women and [has] been relying on Japanese and American data,” said Kang Sung-hyun, an academic on the research team.

He added: “It is crucial for South Korea to have our own data for the issue of comfort women.”

Some have estimated that as many as 200,000 women were victims of the practice, which remains a source of tension between the two countries.

Earlier this year, Japan announced it would recall its ambassador to South Korea and suspend economic talks in response to the placing of a “comfort woman” statue in the Korean port city of Busan.

In 2015 the two governments attempted to smooth strained bilateral ties by agreeing that the issue would be “irreversibly resolved” if both sides fulfilled their set obligations.

Japan apologised and pledged one billion yen (£6.86 million) for a fund to help victims.