North Korea said on Saturday it will elect new party leaders at a rare meeting in September in what analysts say could be a move to strengthen a campaign to hand over power from supreme leader Kim Jong Il to his youngest son.

Mr. Kim, who suffered an apparent stroke in 2008, is believed to be grooming his youngest son, Kim Jong Un, to succeed him as leader of the nuclear—armed communist nation of 24 million. His health has raised regional concerns about instability and a possible power struggle if he were to die without naming a successor.

North Korea’s ruling Workers’ Party will convene its conference in early September to elect “its highest leading body,” the country’s official Korean Central News Agency reported. The report did not elaborate.

The planned conference, the first since 1966, sparked speculation that the North could publicly announce Kim Jong Un as his father’s successor by giving him senior party jobs.

Mr. Kim Jong Il was tapped in 1974 to succeed his father, the North’s founder Kim Il Sung. The succession decision was made public in a 1980 party convention. Mr. Kim Jong Il formally assumed leadership upon his father’s death in 1994.

“Kim Jong Un was named as a successor last year, though it was not made public to the outside world,” Cheong Seong—chang, a senior analyst at the security think—tank Sejong Institute, south of Seoul, citing South Korea’s top spy agency, said.

The conference “should be seen as a stage to publicize Mr. Kim Jong Un as a successor,” Mr. Cheong said, noting he could be elected to the party’s key positions, including a secretary of the party’s central committee.

The National Intelligence Service was not immediately available for comment on Saturday.

Little is known about Mr. Kim Jong Un, including his exact age, though he is believed to be in his mid—20s. Mr. Kim Jong Il’s former sushi chef says in a 2003 memoir that the son looks and acts just like his father and is the leader’s favourite.

South Korea’s spy chief Won Sei—hoon said on Thursday that North Korea has launched a propaganda campaign aimed at making its people adore the junior Kim.

Mr. Won told lawmakers North Korea has been publicizing songs and poems praising Mr. Kim Jong Un and holding poem—reciting contests, said Lee Kyung—jik, an aide to Hwang Jin—ha, a ruling party lawmaker who attended a closed—door parliamentary session on Thursday. Mr. Hwang himself could not reached for comment.

North Korea is focusing on the succession issue because of Mr. Kim Jong Il’s health, and the junior Kim frequently travels with his father on inspection visits to army bases and factories, Mr. Won was quoted as saying.

Mr. Won also said Mr. Kim’s memory appears to be failing and he has made illogical comments during inspection trips due to side effects of the stroke, South Korea’s mass—circulation Chosun Ilbo newspaper reported on Saturday, citing unidentified lawmakers who attended Thursday’s parliamentary session.

On Friday, at least 120,000 North Koreans held an anti—U.S. rally in Pyongyang on the 60th anniversary of the outbreak of the Korean War. Kim Ki Nam, a senior North Korean party official, told the gathering that North Korea “will continue to strengthen nuclear deterrence for self defence,” according to footage shot by broadcaster APTN.

North Korea is grappling with economic woes that have worsened after a botched currency reform last year and tension with the outside world over its nuclear program and the sinking of a South Korean warship in late March.

South Korea has accused the North of torpedoing the warship Cheonan and is seeking to have the U.N. Security Council penalize it. The North denies the allegation and has warned any punishment would trigger war.

The two Koreas are still technically at war because their 1950—53 Korean War ended with an armistice, not a peace treaty.

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