South Korean prosecutors said Sunday they have resumed their investigation of a Japanese band accused of defaming victims of Japanese colonial-era sexual slavery.

In February 2013, former "comfort women," an euphemistic term for women sexually enslaved for Japanese soldiers during World War II, received music CDs and song lyrics from Japanese band "Scramble" that called them prostitutes and said they should die. 

The CDs were sent to a shelter for the victims in Gwangju, south of Seoul, a day before the anniversary of the March 1 Independence Movement Day that celebrates the start of the nationwide struggle against Japanese colonial rule that lasted from 1910 to 1945.

Having made little progress in the investigation for nearly a year, the prosecution said it has asked the Japanese law enforcement agencies for cooperation on the case. It said it requested information on the identity and home addresses of the band members who are using aliases but did not give out further details.

Not much is known about the band, which participated in an event held by a Japanese right-wing activist prosecuted in South Korea.

Historians say up to 200,000 women, most of them Korean, were coerced into sexual servitude by the Japanese army at front-line brothels during World War II when the Korean Peninsula was a Japanese colony.

Japan has acknowledged that its wartime military used sex slaves. However, Tokyo refuses to officially apologize or compensate the victims, claiming that the issue was settled by a 1965 treaty that normalized relations between the two countries.

The comfort women issue is becoming increasingly urgent as most surviving victims are well over 80 years old.

During a visit to Seoul earlier this week, former Japanese Prime Minister Tomiichi Murayama expressed hope that the current Japanese leader, Shinzo Abe, would acknowledge Tokyo's colonial aggressions. (Yonhap News)