Colonial Japan forced hundreds of Korean girls into hard labor to produce its war supplies, a report showed Monday, adding to the grievances of Koreans against Japan's exploitation in war times that also include sexual enslavement.

The average age of Korean females subjected to forced labor came to 16.46 years, according to the report on 1,039 cases of coerced labor on Korean women by Japan during its colonial rule from 1910-45. 

Among those drafted for factory jobs, the average age came out to be an even lower 13.2 years, according to the report by the

Prime Minister's Office's forced labor investigation commission.

The number of victims here does not include Korean women who were forced into sexual enslavement at front-line brothels for Japanese soldiers during World War II.

"Japan set up a new law banning labor of children aged 14 or younger at factories in accordance with international conventions back in the 1920s, but it did not apply the rule to Koreans," said Chung Hye-kyung, a commission official in charge of the investigation.

Of the forced labor cases, the largest share of 59 percent was mobilized for labor at factories, followed by 143 cases for mining, 121 cases at plantations and 17 cases at construction sites, the report showed.

Some 51 percent were sent to Japan, and 31 percent served at workplaces on the Korean Peninsula, with the rest being drafted overseas including to China and Russia.

Of the victims, 27 died on site, including nine children aged 14 or younger, the commission said.

The number of forced mobilization cases had surged along with its intensified Pacific War in the 1940s, from 190 cases in 1942 to 231 cases in 1943 and to 272 cases in 1944, according to the report.

"Our investigation into those cases showed that many of the victims have suffered from aftereffects of hard labor, such as Parkinson's disease. Some took their own lives after suffering from mental disorders," she said.

As a way of resolving the wartime atrocities, the commission called on the public to pay more attention to the cases and urged Japan to disclose data related to forced labor.

"The South Korean government also needs to devise measures to learn more about such unknown cases and to compensate the victims," Chung said.

The Japanese government as well as companies that mobilized forced laborers have refused to make any compensation, saying all issues regarding its colonial rule, including sex slavery and monetary reparations, were covered by a 1965 package agreement that normalized relations between the two nations. (Yonhap News)