North Korean leader Kim Jong-un has managed to strengthen his power base since the execution of his uncle Jang Song-thaek, but he faces some domestic and external risks in the long run, a South Korean official said Tuesday.

In particular, the elevated stature of the two powerful agencies -- the State Security Department and the Organization and Guidance Department of the Workers' Party of Korea -- could serve as a double-edged sword for the young leader, according to the official.

After a show trial in December last year, Pyongyang executed Jang, once a guardian of Kim and the No. 2 leader in the communist nation, on charges of treason and corruption, among others.

"The power of Kim Jong-un has strengthened in the short term over the past one year since the execution of Jang," he told reporters on background.

But the future of Kim's leadership for the longer term is still uncertain, as the two key North Korean organizations may become influential enough to back a different leader, he said.

The official was speaking about the government's analysis of the North's political situations following the purging of Jang.

The Kim regime is still in the works of clearing the vestige of the Jang era, while continuing efforts to tighten Kim's grip through the frequent changes of top officials and idolization projects, said the Seoul official.

Kim is also confronted with external challenges in the absence of Jang, who was Pyongyang's point man on Beijing.

Political exchanges between the two sides have notably decreased since the loss of Jang and major bilateral economic cooperation projects have come to a halt, the official said.

"It looks like that North Korea has not found the replacement to Jang in terms of relations with China," he said.

He also said Jang's wife, Kim Kyong-hui, seems to be alive despite some press reports that she was killed or committed suicide.

If she was dead, the North's media would have published an obituary, he added.

He agreed that there is a chance of the North's leader holding summit talks with Russian President Vladimir Putin next year, as he will begin full-fledged efforts for his own diplomatic accomplishments. (Yonhap)