A group of U.S. congressmen Tuesday urged Japanese Prime Minister Shinzo Abe to apologize for Japan's wartime sex slavery when he addresses Congress next week.

Abe is scheduled to make a speech at a joint meeting of the House and Senate when he visits Washington next week for summit talks with President Barack Obama, an honor that would make him the first-ever Japanese prime minister to do so.

Critics have said Abe is unworthy of the privilege because he has attempted to whitewash Japan's militaristic past and wartime atrocities, especially sexual enslavement, refusing to acknowledge the country's responsibility and compensate victims.

"When Japanese Prime Minister Shinzo Abe addresses a joint meeting of Congress next week on April 29, he has the opportunity to do right by these women. He can make a full, unequivocal and formal apology on behalf of the Japanese government," Rep. Mike Honda (D-CA) said.

Honda, who has long spoken out for the victims of sexual slavery, used the 20-minute speech to explain in detail the sufferings of the victims and how Japan's government has attempted to whitewash the crime and evade responsibility.

As one surviving victim, Lee Yong-soo of South Korea, looked on from the audience, Honda explained how she, then 16 years old, was kidnapped in 1944 and forced to work as a sex slave in Taiwan while experiencing beatings, torture and disease.

"There is nothing more important right now than for a democratic country like Japan to apologize for its past mistakes. A government is a living, breathing organism that is responsible for its past, present and its future," Honda said.

He also urged Tokyo to learn from Germany.

Historians estimate more than 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.

Fewer than 100 victims are now alive and they are dying by the day, Honda said.

"They deserve what has been due to them for the past 70 years.

They deserve the justice that has been denied them," he said.

The lawmaker also rejected claims that Japan has apologized enough.

"To those people, I would say, given this continued revisionist attempts, for every step forward toward peace and reconciliation, the government of Japan takes two steps backwards," he said.

"Enough is enough. Seventy years later, it's time for Prime Minister Abe to be clear and unequivocal and issue an irrefutable apology."

Other congressmen also took the floor to make the case for Abe's apology.

Rep. Steve Israel (D-NY) said the planned Abe address "must be honest" and address Japan's wartime history, including the sexual slavery, stressing that ignoring past atrocities is to "ensure a very troubling future."

"These wounds need to be closed. They need to be healed and Prime Minister Abe can do that closure, can do that healing by exposing those wounds to the light of the truth and an apology, and I'm hopeful that he will do this on this floor when he addresses us next week," he said.

Rep. Bill Pascrell (D-NJ) also said he has been a co-sponsor of Congress resolutions urging Japan to apologize for the sexual slavery issue, and hopes Abe's visit next week will "lay the foundation for healing and humble reconciliation by addressing the historical issue of the comfort women."

Charles Rangel (D-NY) said he wants to see "the stigma of the lack of credibility" removed from Japan.

"Let's get this behind and move forward," he said. (Yonhap)