TOKYO, May 20 (Reuters) - Saudi Arabian Crown Prince Mohammed bin Salman has postponed his visit to Japan scheduled to begin on Monday due to King Salman's health issue, Japan's Chief Cabinet Secretary Yoshimasa Hayashi said.

The de facto Saudi leader had been scheduled to meet with Japanese Emperor Naruhito and Prime Minister Fumio Kishida during trip scheduled for May 20-23.

Saudi Arabia's state news agency on Sunday reported that 88-year-old King Salman will undergo treatment for a lung inflammation. (Reporting by Kaori Kaneko; Writing by John Geddie Editing by Chang-Ran Kim)