TOKYO, April 17  A group of Japanese researchers on Tuesday publicly challenged Prime Minister Shinzo Abe’s denials that Japan’s military coerced women into sexual slavery during World War II, citing reports compiled by Allied investigators immediately after the war.

The reports, based partly on interrogations of Japanese prisoners, were originally submitted to the Tokyo war crimes trials, which ended in 1948, as evidence of atrocities by Japan during its wartime expansion across Asia. The reports include accounts of Japanese soldiers and sailors rounding up foreign women for use as sex slaves, euphemistically known here as comfort women.

Mr. Abe and other conservatives have repeatedly said there was no evidence that Japan’s military had a direct hand in forcing women into sexual slavery. Many Japanese conservatives have cited the lack of corroborating official documents to dismiss the testimony of former sex slaves, who started coming forward in the 1990s to tell their stories.

While the evidence presented Tuesday was not new, the group’s members said they felt obliged to respond to Mr. Abe’s denials. The group’s public rebuttal of Mr. Abe was a rare protest in a country where the prime minister’s remarks had stirred little outcry. The reaction has been much stronger in the rest of Asia, where memories of Japanese aggression remain raw, highlighting Tokyo’s isolation on war history.