Ammon News - Embattled Japanese Prime Minister Shigeru Ishiba will resign to avoid a split within his ruling party, a source close to the premier said on Sunday, pitching the world's fourth-largest economy into fresh political uncertainty.

A spokesperson for the Prime Minister's Office did not immediately have a comment when contacted by Reuters, but the government said Ishiba would hold a press conference at 6 p.m. (0900 GMT).

Since the former defence minister came to power in September last year, his coalition has lost its majorities in elections for both houses of parliament amid voter anger over rising living costs.

He had refused calls from within his Liberal Democratic Party - which has ruled Japan for almost all of the post-war era - to step down and take responsibility for the upper house loss in July.

Instead, he has focused on trying to iron out the final details of a deal with the United States on trade tariffs that have roiled its critical automotive industry.

Concern over political uncertainty led to a sell-off in the yen and Japanese government bonds last week, with the yield on the 30-year bond hitting a record high on Wednesday.

Reuters