North Korea's new leader Kim Jong-un has been named the "first secretary" of the Workers' Party, an apparent newly-created top post of the party, the North's state media said Wednesday, ahead of a planned rocket launch.

Kim's late father, Kim Jong-il, was also named "eternal" general secretary of the ruling party at a crucial party conference held earlier in the day, the Korean Central News Agency (KCNA) said.

The news came as North Korea has started fueling a long-range rocket to launch a satellite into orbit, drawing international condemnations that the launch is a cover for testing its improved ballistic missile technology.

At the party conference, Kim Jong-il, who died of a heart attack in December, was declared "eternal general secretary of the WPK (Workers' Party of Korea) in reflection of the unanimous will and desire of all the party members and other people," KCNA said.

Meanwhile, North Korea's state radio said it will air an "important broadcast" later Wednesday, soon after the news of current and late leaders' new titles were announced. (Yonhap)