Japan's Prime Minister Shinzo Abe and US President Donald Trump wait for a meeting in the Oval Office of the White House on February 10, 2017 in Washington, DC.

Japanese Prime Minister Shinzo Abe is finalizing details for a summit with President Donald Trump on April 18 to discuss strategy before a proposed meeting between North Korean and U.S. leaders, a ruling party official told Reuters on Wednesday.

Abe will also likely ask Trump to exempt Japan from his steel and aluminum tariffs, said the official, who has been briefed on the matter and asked not to be identified.

Abe, speaking at a parliamentary committee, said Japanese steel products were helping to make U.S. auto makers more competitive and cheaper for American consumers.

"Protectionism, at first glance, appears to benefit a nation which exercises it, but it is not necessarily so," Abe said. "Japan wants to be a flag bearer to promote a free trade which will bring a win-win situation to each nation."

His finance minister, Taro Aso, echoed that view and said some of responsibility for the trade imbalance rested with the United States.

"I understand the U.S. position that it cannot continue with a trade deficit, but the United States itself should make efforts," Aso told the same committee.

The meeting between Abe and the U.S. leader is expected to be held at Trump's Mar-a-Lago retreat in Florida, according to the source. North Korea's Kim Jong Un is set to meet South Korean President Moon Jae-In in April and then possibly Trump in May.