Pyongyang: Kim Jong Il's son was identified on Monday as head of a top decision-making body of the ruling Workers' Party, a post that now gives him authority over political as well as military matters in North Korea.

A week after state media reported leader Kim Jong II's December 17 death, the campaign to install successor Kim Jong Un gained momentum.

On Saturday, state media referred to him as ‘supreme leader’ of North Korea's 1.2 million-strong armed forces and said the military's top leaders had pledged their loyalty to him.

On Monday, a newspaper said North Korean soldiers are upholding a slogan urging them to dedicate their lives ‘to protect the party's Central Committee headed by respected Comrade Kim Jong Un.’

Kim Jong II, who state media said died of a heart attack, ruled North Korea as head of three main state organs, the Workers' Party, the Korean People's Army and the National Defence Commission.

His father, North Korea founder Kim II Sung, meanwhile, remains the nation's ‘eternal president’ long after his 1994 death.

Kim Jong Un, who is in his late 20s and was revealed last year as his father's choice among three sons for successor, is the third generation Kim to rule the nation of 24 million.

He was named a vice chairman of the Central Military Commission of the Workers' Party, but was expected to ascend to new military and political posts while being groomed to become the next leader.

It came as two private South Korean delegations arrived in Pyongyang to pay their respects to Kim Jong II.

The slogan, which state media had frequently used when rallying support for Kim Jong II, made clear the son is quickly moving toward leadership of the Workers' Party, one of the country's highest positions, in addition to the military.

The newspaper on Sunday urged the people to become ‘eternal revolutionary comrades’ with Kim Jong Un, ‘the sun of the 21st century.’

North Korea refers to Kim II Sung as the ‘sun’ of the nation and his birthday is celebrated as the ‘Day of the Sun,’ and state media has sought to emphasise Kim Jong Un's role in carrying out the Kim family legacy throughout his succession movement.