North Korean leader Kim Jong-un has been named first secretary of the ruling Workers' Party.

The North's state-run Korean Central News Agency (KCNA) said that Kim was given the title at the fourth conference of the Workers' Party delegates held in Pyongyang on Wednesday. Kim is also the vice chairman of the party's Central Military Commission.

The former leader and Kim Jong-un's father, Kim Jong-il, was given the posthumous title of "eternal General Secretary of the Workers' Party."

The KCNA said the appointment of Kim Jong-un as the party's first secretary was an expression of "absolute support and trust of all party members, soldiers of the People's Army, and the people."

Kim Jong-un strengthened his grip on power with the new title about four months after the death of his father in December last year.