Japanese Prime Minister Shinzo Abe will deal properly with historical issues that have strained relations with South Korea when he visits the United States next week, Tokyo's top envoy to Washington said Tuesday.

Abe is set to make a weeklong visit to the U.S. amid calls for him to use the trip, which includes an address at a joint meeting of Congress, to offer a sincere apology for Japan's wartime atrocities and mend fences with South Korea.

"I don't have any worry about it and I think the prime minister would respond to all this issue properly," Amb. Kenichiro Sasae said during a think-tank discussion in response to a question how the historical issues will be dealt with during Abe's visit.

The envoy stressed Abe has made clear that his cabinet honors all of Japan's previous statements of apology, including the 1995 Murayama and the 1993 Kono statements that have served as the basis for Japan's relations with South Korea.

"I think that's a very strong, and simple, but very strong statement of his positions on this," he said of Abe's position on honoring previous statements during the discussion at the Center for Strategic and International Studies. "He's saying that he's upholding all this position in its entirely."

Relations between Seoul and Tokyo have been badly strained for years, due mainly to Tokyo's attempts to whitewash its wartime atrocities and colonial occupation, especially its sexual enslavement of women for its troops during World War II.

Frayed relations between the two allies have been a key cause for concern for the U.S. as it seeks to bolster three-way security cooperation seen as a key pillar for President Barack Obama's "pivot to Asia" initiative aimed in part at keeping a rising China in check.

Abe's trip, including an address to a joint session of Congress, is seen as a key gauge of how the Seoul-Tokyo ties will go, amid concerns the relations are unlikely to get any better unless Abe offers a sincere apology for Japan's imperialistic past and wartime atrocities.

The congressional speech would be the first by a Japanese prime minister.

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

Also Tuesday, State Department acting spokeswoman Marie Harf reiterated the U.S. position that historical issues should be dealt with "in a manner that promotes healing and reconciliation for all parties."

"We, of course, believe that strong and constructive relations between countries in the region promote peace and stability and are in their interests, certainly in our interest as well," she said at a regular press briefing.

Harf also said that Secretary of State John Kerry will host Abe in his hometown of Boston on April 26. (Yonhap)