North Korean leader Kim Jong II has designated his youngest son Kim Jong Un as his successor, South Korean lawmakers told on Tuesday.
Members of South Korea's National Assembly and intelligence community were informed by the government of "such ongoings (of succession), and that they (the North Koreans) make loyalty pledges to Kim Jong Un", opposition lawmaker Park Jie Won was quoted as saying by the Yonhap news agency.
On Monday, an informed source told DPA that contrary to earlier reports, the 25- or 26-year-old Jong Un, the third of Kim's three known sons, was elected in March to the Supreme People's Assembly although no official confirmation has been given.
Yonhap said North Korea's leader informed the country's key bodies, including the Korean People's Army, the leaders of the Supreme People's Assembly, the cabinet and its embassies immediately after Thursday's nuclear test he had designated Kim Jong Un as successor.
Speculation over who might take over from Kim, 67, has escalated since South Korean intelligence services reported that he had suffered a stroke last year.
The Kim family has ruled North Korea since 1948 beginning with Kim's father, Kim Il Sung. Kim Jong Il took over when he died in 1994.
Swiss-educated Jong Un is the son of Kim Jong Il's third wife, Ko Yong Hi, and is little known. Ko died in 2004 of breast cancer, according to media reports.
Speculation about the country's next leader came at a time of escalating tensions on the Korean Peninsula this year after North Korea carried out its second nuclear test last week, launched a series of missiles and repeatedly threatened South Korea.