PYONGYANG, North Korea (AP) -- North Korea's state media on Monday called Kim Jong Il's heir the head of the ruling Workers' Party Central Committee, a job that gives Kim Jong Un power over one of the country's highest decision-making bodies more than a week after his father's death.

The reference in a commentary by the North's main Rodong Sinmun newspaper came as a former South Korean first lady and a prominent business leader traveled with two private delegations to North Korea to pay respects to Kim Jong Il, who is being mourned by millions as the North prepares for his funeral Wednesday.

North Korean soldiers, Rodong Sinmun said, 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 Il's youngest son is in his late 20s and was unveiled in September 2010 as his father's choice as successor.

The slogan, which state media had frequently used when rallying support for Kim Jong Il, suggests the heir will likely be appointed as Workers' Party general secretary, the ruling party's top job and one of the country's highest positions.

North Korea is in official mourning for Kim until after a memorial Thursday. But the country is also offering hints about Kim Jong Un's rise as ruler. North Korea began hailing him as ``supreme leader'' of the 1.2-million strong military over the weekend.

Kim Jong Un will be the third-generation Kim to rule the nation of 24 million.

Also Monday, a total of 18 South Koreans crossed the heavily fortified border for a two-day trip that includes a visit to Pyongyang's Kumsusan Memorial Palace where Kim's body is lying in state, according to Seoul's Unification Ministry.

The two groups are led by the widow of former President Kim Dae-jung, the creator of the engagement ``sunshine'' policy with the North who held a landmark summit with Kim in 2000, and Hyundai Group Chairwoman Hyun Jeong-eun, whose late husband had ties to the North. The North sent delegations to South Korea when the women's husbands died.

South Korea has only allowed the two groups to visit and pay condolences for the death of Kim on Dec. 17. That has angered Pyongyang, which subsequently warned that obstructing mourning trips to the North would lead to ``catastrophic consequences'' for relations between the rivals.

Even as North Koreans brave frigid weather to visit mourning stations set up at landmarks around the country, the state media are providing details about Kim Jong Un's rise to power.

Koreans should become ``eternal revolutionary comrades'' with Kim Jong Un, ``the sun of the 21st century,'' Rodong Sinmun newspaper said Sunday in a commentary carried by the official Korean Central News Agency.

State television also showed Sunday footage showing Kim Jong Un's uncle and key patron, Jang Song Thaek, wearing a military uniform with a general's insignia, a strong sign he'll play a crucial role in helping the young man hold a grip on power and inherit his father's trademark ``military-first'' policy. Seoul's Unification Ministry said it was the first time Jang, usually seen in business suits, had been shown wearing a military uniform on state TV.

Jang, a vice chairman of the powerful National Defense Commission, is the husband of Kim Kyong Hui, younger sister of Kim Jong Il and a key Workers' Party official. South Korean lawmakers say intelligence officials have predicted that Jang and his wife will play larger roles supporting Kim Jong Un.

The North's state TV repeatedly showed footage Sunday of wailing uniformed soldiers, many with shaved heads, and other citizens professing their tear-choked longing for Kim Jong Il as they visited mourning sites.