The source did not have further details on the meeting between the billionaire entrepreneur investor and the king, who is on a state visit to Japan this week.

The Saudi embassy did not immediately respond to a telephone request for comment.

Saudi Arabia and SoftBank agreed in October to pursue the SoftBank Vision Fund, which would be one of the world's largest private-equity investors and a potential kingpin in the industry.

(Reporting by Yoshiyasu Shida; Writing by William Mallard; Editing by Chang-Ran Kim)