An 88-year-old South Korean woman forced to become a sex slave in Japanese military brothels during World War Two on Friday called on Japanese Prime Minister Shinzo Abe to apologize and restore her "honor" when he visits Washington next week.

The issue of "comfort women", as those forced to work in the brothels are known, has long been a flash point in Japan's ties with Asia and is gaining renewed attention ahead of the 70th anniversary of the end of World War Two later this year.

Many Japanese conservatives, including Abe, say there is no proof of direct state involvement in kidnapping the women. Abe also wants to recast Japan's wartime past with a less apologetic tone, and his stance on history will be scrutinized when he visits the United States.

Protests are likely, including over the comfort women issue.

"He should go there and acknowledge the wrongs that were committed in the past ... and apologize for it," Kim Bok-dong told a Tokyo news conference.

Kim was taken away to what she was told would be a sewing factory when she was 14. Instead, she ended up at a brothel in China before being transferred around Southeast Asia as the war went on. When she protested, she was beaten on the head until her face went numb.

"Prime Minister Abe says there's no evidence. I'm the evidence, I'm alive," she said, through a translator. "To deny this doesn't exist is absurd."

Abe has said he would uphold apologies for the war, including a 1995 landmark statement by then-premier Tomiichi Murayama. But he has also said he wanted to issue forward-looking remarks in his own words, sparking concern he wants to water down past apologies.

In a speech in Jakarta this week, Abe alluded to Tokyo's remorse in the past over World War Two without issuing a fresh apology.

Kim said her experiences left her body covered with scars and unable to bear children.

"I'm almost 90, but I don't know what love is. I was dragged off while I was still a girl," she added.

"...But I cannot die yet, there are things I need to do. I need an official apology. I need my dignity and honor."