Kim Jong-il, North Korea's reclusive leader, has promoted his son, Kim Jong-un, to the rank of general in the powerful military, just hours before a key meeting to determine the country's leadership, state media reports.
Analysts believe the promotion makes Kim the likely heir apparent to his father, who is reported to be in ill health.
Kim, thought to be born in 1983 or 1984 and partially educated in Switzerland, is the youngest of senior Kim's three known sons, none of whom had ever been mentioned in the secretive North's official media.
State media also reported on Wednesday that Kim was named the vice-chairman of the ruling Workers' Party's powerful central military commission.
Also promoted to general was Kim Kyong-hui, the ailing leader's sister, KCNA news agency reported.
The ruling Workers' Party of Korea convened a rare meeting on Tuesday in a move analysts expected to kick off the succession process of the leader's son.
Al Jazeera's Tony Birtley, reporting from Seoul, said it was important for Kim to gain as much support as possible for his son so that there will be less opposition later.
"Very strange things have been happening in the last 18 months. Possible opponents to these appointments have died in mysterious circumstances.
"The army which carries a lot of weight in North Korea must have endorsed [Kim's] promotion to a four-star general, so they are moving in the right direction."
Our correspondent said the question, however, remains as to whether there will be any instability or power struggle in North Korea when Kim dies.
The widely anticipated meeting will be the party's first major gathering since a landmark congress in 1980 where then 38-year-old Kim Jong-il made his political debut. That appearance confirmed he was in line to succeed his father, Kim il Sung, the founder of North Korea.
Kim Jong-il, the current North Korean leader, has reportedly been in ill health for months [EPA]
The senior Kim came to power when his father died of heart failure in 1994, setting in motion the communist world's first hereditary transfer of power.
Kim Jong-un has been elected to attend the party conference as a delegate of the Korean People's Army, South Korea's Chosun Ilbo newspaper reported on Monday, citing a source in North Korea it did not identify.
After he was elected as a delegate, the party central committee put out an internal propaganda proclaiming him to be Jong-il's sole successor, the report said, citing the unnamed North Korean.
Andrei Lankov, a professor of Korean Studies at Seoul's Kookmin University, told Al Jazeera it appeared that North Korea was making serious preparations for the succession plan.
"Jong-un is well-positioned to run the country or at least to be the supreme leader, formally and technically a figurehead. He is very young, very inexperienced… and in all probability will be controlled by his uncle and his aunt," he said.
Backing by the military is considered a prerequisite for the succession to be carried out smoothly in a country that operates on a "military first" policy where priority is given to the armed forces.
The senior Kim was officially chosen as successor in 1972, when he was elected to the party's central committee, and the same scenario could hold true for his.
The question of who will take over from the senior Kim, believed to suffer from a host of ailments, is important to regional dynamics as well as security, because of North Korea's active nuclear and missile programmes, and regular threats it makes against rival South Korea.
Source: Al Jazeera and agencies