Prime Minister Shinzo Abe on Wednesday expressed "deep remorse" over Japan's actions toward neighboring Asian nations during World War II, but stopped short of a full apology for mass sexual slavery.

"Post war, we started out on our path bearing in mind feelings of deep remorse over the war," Abe said in a historic address to a joint meeting of the US Congress.

"Our actions brought suffering to the peoples in Asian countries. We must not avert our eyes from that."

Abe also expressed his "eternal condolences" to US troops killed in World War II.

"On behalf of Japan and the Japanese people, I offer with profound respect my eternal condolences to the souls of all American people that were lost during World War II," he said to rousing applause from lawmakers.