Tokyo, Sep 20 (Xinhua) Japanese Chief Cabinet Secretary Shinzo Abe was elected president of the ruling Liberal Democratic Party (LDP) on Wednesday and will succeed Junichiro Koizumi as Japan's next prime minister.

Abe will get a three-year term as LDP president and step on to the post of prime minister because the ruling alliance, made up of the LDP and its coalition partner New Komeito party, holds a majority in the lower house.

The newly elected LDP leader will also become Japan's first prime minister born after World War II.

The LDP leadership lineup is expected to be decided on Monday and Abe will announce his cabinet next Tuesday, the day for the parliaments to appoint him as Koizumi's successor in an extra Diet session.

In his policy platform announced during the campaign, Abe put replacing the current US-drafted constitution with Japan's own on top of his agenda, and called for strengthening the premier's decision-making powers on defense and foreign affairs.

While accentuating on a stronger Japan-US alliance and describing it as "the most important thing" for Japan's diplomacy and national security, Abe pledged to try to improve relations with Asian neighbours as well.

He also included seeking permanent membership of the UN Security Council, drastically reforming the education system and building sustainable social security system on his policy agenda.