SEOUL: North Korean leader Kim Jong Il has put his youngest son in charge of the country's spy agency as a prelude to handing over control of the communist regime, a news report said Wednesday.

Kim visited the headquarters of the State Security Department in March, along with his 26-year-old son, Kim Jong Un, and told agency leaders to "uphold" his third son as head of the department, the Dong-a Ilbo newspaper reported citing an unnamed source.

Kim also told department leaders to "safeguard comrade Kim Jong Un with (your) lives as you did for me in the past," and gave them five foreign-made cars, each worth some $80,000, as gifts, the mass-market daily said.

It said Kim visited a college that educates spy agents last month and made similar remarks there.

Pyongyang's State Security Department is the backbone of Kim's harsh rule over the totalitarian nation. It keeps a close watch over government agencies, the military and ordinary people for any signs of dissent. It also engages in spy missions abroad.

The move to put Kim Jong Un in charge of the agency illustrates the elder Kim's concern about any possible backlash that the father-to-son succession could prompt, the Dong-a said.

The paper also said the younger Kim oversaw the handling of two American journalists detained in March while on a reporting trip to the China-North Korea border. The reporters were sentenced to 12 years of hard labor earlier this month for illegal border crossing and hostile acts.

In Washington, State Department spokesman Ian Kelly told reporters that Mats Foyer, Sweden's ambassador in North Korea, visited the reporters Euna Lee and Laura Ling in Pyongyang on Tuesday. Sweden serves as the U.S. protecting power in North Korea.

Foyer has been in "constant contact" with the North, pressing for access, Kelly said. He said the U.S. was "pursuing many different avenues" to secure their release, but he would not elaborate.

South Korea's main spy agency, the National Intelligence Service, said it could not confirm the Dong-a report.

Who will eventually rule the nuclear-armed North has been the focus of intense media speculation since leader Kim, 67, reportedly suffered a stroke last summer. That sparked regional concerns about instability and a possible power struggle if he died without naming a successor.

The succession talk has further intensified after Seoul's spy agency reported to lawmakers early this month that the regime in Pyongyang notified its diplomatic missions and government agencies that Kim Jong Un will be the next leader.

Seoul's JoongAng Ilbo newspaper reported earlier this month that he had been given the title of "Brilliant Comrade," another sign that the regime was preparing to name him as successor.

Kim Jong Il inherited North Korea after his father and founding leader Kim Il Sung died in 1994.

On Tuesday, the North's main Rodong Sinmun newspaper carried a remark by Kim Jong Il that could be seen as a justification of the father-to-son succession.

"Our resolution is winning victory after victory because the bloodline" of the country's self-reliance ideology has been succeeded through generations.