The United States said Thursday victims of Japan's wartime sexual slavery were trafficked by the country's military in a rebuttal of a Japanese ruling party committee's claim that they were never coerced.

The State Department issued the comment, calling the atrocity "a terrible, egregious violation of human rights" and urging Japan to handle the issue and other historical matters in a way that strengthens relations with neighboring nations.

"As the United States has stated many times, the trafficking of women for sexual purposes by the Japanese military during World War II was a terrible, egregious violation of human rights," State Department spokesperson Katina Adams said in comments emailed to Yonhap News Agency.

"The United States has consistently encouraged Japan to approach this and other issues arising from the past in a manner that is conducive to building stronger relations with its neighbors," she said.

The spokesperson also stressed that Washington's policy on the trafficking of women for sexual purposes remains the same: that the U.S. continues to emphasize the importance of "approaching historical legacy issues in a manner that promotes healing and reconciliation for all parties."

The Liberal Democratic Party committee made the claim earlier this week in a policy recommendation urging Prime Minister Shinzo Abe to work proactively to refute "misunderstandings" in the international community that there was forcible recruitment of women for troops during World War II.

The claim is yet another example of Japanese politicians backtracking on the country's past statements of apology in an attempt to whitewash its wartime actions, and underscored the difficulty getting Japan to acknowledge historical facts.

The recommendation came as Abe has been preparing to issue a statement next month to mark the 70th anniversary of Japan's defeat in the war amid calls for him to offer an unequivocal apology for the atrocity so as to repair badly frayed ties with South Korea.

"When Prime Minister Abe came here in April, we had expected him to make remarks on historical issues, but we generally feel that (what he said) was a little insufficient," a senior South Korean official said on condition of anonymity. "In a statement around the 70th anniversary, we anticipate to hear what would represent a step forward."

Historians estimate that up to 200,000 women, mainly from Korea, which was a Japanese colony from 1910 to 1945, were forced to work in front-line brothels for Japanese soldiers during World War II. But Japan has long attempted to water down the atrocity.

Such efforts have intensified after the nationalist Abe came to power.

Abe's upcoming statement will be watched closely as it is considered a second chance for him to resolve historical tensions with South Korea after failing to do so during his U.S. visit in April.

The sexual slavery issue has been the biggest thorn in frayed relations between Japan and South Korea, with Seoul demanding Tokyo take steps to address the grievances of elderly Korean victims of the atrocity and Japan refusing to do so. (Yonhap)