Mr Ishiba has been under growing pressure to step down as his ruling Liberal Democratic Party (LDP) and its junior coalition partner, Komeito, lost their majority in the 248-member upper house, the smaller and less powerful of Japan's two-chamber parliament on Sunday, shaking his grip on power and Japan's political stability.

Japanese Prime Minister Shigeru Ishiba vowed to remain in office on Monday after his ruling coalition suffered a bruising defeat in upper house elections, prompting some of his own party to deliberate his future as the opposition weighed a no-confidence motion.

Japan's Prime Minister Shigeru Ishiba is set to announce that he will step down from the top job, according to local media.