TOKYO - Japanese Prime Minister Fumio Kishida will double as foreign minister until he relaunches the Cabinet after the Japanese parliament holds a special session next week, local media reported Thursday.

After Akira Amari resigned from the post of the secretary-general of Japan's ruling Liberal Democratic Party (LDP) due to his shock defeat in a single-seat district in Sunday's House of Representatives election, the party officially decided to appoint Foreign Minister Toshimitsu Motegi to the party's No 2 post.

Motegi, former policy chief of the LDP, easily secured his seat in his constituency Tochigi Prefecture in the latest election of the lower chamber.

Former education minister Yoshimasa Hayashi will be a candidate to succeed Motegi as foreign minister, local media reported, citing sources.

Under the Japanese Constitution, the Cabinet must resign en masse when the first session of the Diet is convened following a general election. Then, the Diet will choose Kishida as the prime minister in a special session expected to be held next Wednesday, and he will then relaunch the Cabinet.

Kishida told reporters on Thursday "Since I have gained the people's mandate through the general election, I now plan to speedily implement policies" on key issues such as the COVID-19 pandemic and economic challenges.