U.N. Secretary-General Ban Ki-moon said Friday South Korea's President Park Geun-hye had made a "courageous decision" to reach a landmark agreement with Japan on resolving the issue of Japan's wartime sexual slavery.

"History will laud President Park Geun-hye's courageous decision based on her vision," Ban said during his phone call with Park.

Ban also said it is a relief that the two countries reached the agreement before the end of 2015, as it marked the 50th anniversary of the establishment of the bilateral diplomatic relations of Seoul and Tokyo.

South Korea and Japan reached the agreement in talks earlier this week, which centers on Japan's admission of responsibility for the wartime crime and plans to pay reparations to the victims.

The deal included Japan offering reparations of 1 billion yen ($8.3 million).

Historians estimate that more than 200,000 women, mostly Koreans, were forced to work in front-line brothels for Japanese soldiers during the war. Korea was under Japanese colonial rule from 1910 to 1945. The victims are euphemistically called "comfort women."

In December, a former South Korean comfort woman died at age 96, reducing the number of surviving victims in the country to 46.

Some of the victims and their supporters, however, have accused the government of failing to obtain Japan's acknowledgment of legal responsibility and rashly reaching the deal without consulting them. (Yonhap)