An influential Japanese opposition lawmaker called Wednesday on Prime Minister Shinzo Abe to work for more stable relations with the United States and South Korea after rifts over historical disputes.

Seiji Maehara, a former foreign minister and prominent member of the largest opposition Democratic Party of Japan, said that close allies Washington and Tokyo would inevitably have disagreements but should address them privately.

"Behind the scenes, we may fiercely argue with each other. But still we should showcase our strong bond to outsiders," Maehara said in Washington at the Center for American Progress, a left-leaning think tank.

"We have to understand precisely which country would benefit from a worsening of the Japan-US relationship," Maehara said, in a veiled reference to a rising China.

Abe, a conservative who led his bloc to crush the Democrats in the last two national elections, on December 26 paid a pilgrimage to the Yasukuni shrine which honors 2.5 million Japanese war dead and which China and South Korea associate with Japan's past militarism.

The United States, in a rare rebuke of Tokyo, said it was "disappointed" by Abe's visit. An aide to Abe later hit back that it was Japan that was disappointed by the United States.

Maehara did not directly criticize Abe, who is known for his right-leaning views on history, but noted that government leaders during the Democrats' 2009-2012 tenure refrained from visiting the Yasukuni shrine or reviewing Japan's historical apologies.

Abe's government has said that it is reviewing but will not revise Japan's landmark 1993 apology to wartime sex slaves known as "comfort women," an issue that stirs passions in South Korea.

Maehara urged efforts to build relations with South Korea, saying that he was struck during visits to Seoul by widespread opposition to officially pacifist Japan's consideration of allowing "collective self-defense" -- or expanding its doctrine to assist the United States in the event of an attack.

"I believe Prime Minister Abe, as far as he aims at changing the interpretation on collective self-defense, needs to explore every possible way to improve the relations with South Korea," he said.

US President Barack Obama plans to visit Japan next month and added a stop in South Korea amid the strained relations.

A lawmaker from Japan's ruling Liberal Democratic Party, also on a visit to Washington, said that Abe was worried about "inaccurate depictions in the US public."

"Abe is the prime minister who is most concerned about deepening and strengthening the alliance and he is the only prime minister who will be able to produce concrete results," Katsuyuki Kawai, who said he spoke to Abe before his visit, told AFP.

Kawai noted that Abe was pushing ahead on a plan to move a US base within the crowded island of Okinawa, although a local mayor has vowed to resist the plan.

US-Japan relations took a hit in 2009 after the Democrats' election when prime minister Yukio Hatoyama vowed to review the plan to relocate the unpopular Futenma base.