Ruling party presidential candidate Lee Jae-myung and minor candidate Sim Sang-jeung have expressed their disapproval of a 2015 agreement reached by South Korea and Japan to settle the issue of wartime sex slaves, an advocacy coalition said Wednesday.

Lee of the liberal Democratic Party and Sim of the progressive Justice Party stated their positions in response to questions sent last month by the group, which includes the Korean Council for Justice and Remembrance for the Issues of Military Sexual Slavery by Japan.

The candidates said the agreement was inappropriate because it did not properly reflect the wishes of the victims. They also said they will return the 1 billion yen ($8.6 million) Tokyo offered in support money for the victims under the deal.

The agreement was reached during the administration of conservative President Park Geun-hye and includes Japan's apology and acknowledgement of responsibility for its military's sexual enslavement of Korean women during World War II.

The current administration of liberal President Moon Jae-in effectively scrapped the deal after taking office in 2017.

The advocacy coalition said it sent the questions to a total of six presidential candidates but two -- main opposition candidate Yoon Suk-yeol of the conservative People Power Party and Ahn Cheol-soo of the centrist People's Party -- refused to respond.

"In the case of one candidate in particular, we reached out to his team multiple times and even extended the deadline, but failed to get one word out of them," Lee Na-young, the head of the Council, said in a statement.

"We confirmed once again that they are a group consisting mostly of people who, on the one hand, are busy holding hands with the victims as if they care and showing up at events, but on the other hand, call for the abolition of the Ministry of Gender Equality and Family and deny the existence of structural gender discrimination," she said, referring to Yoon.

Lee said she "earnestly" requests all presidential candidates lead the pursuit for truth and justice and work to draw a sincere apology and admission of responsibility from the perpetrators of abuse.

Historians estimate that 200,000 women, mostly from Korea, were forced to work in Japanese front-line brothels during the war. The victims are euphemistically referred to as "comfort women." (Yonhap)