North Korea's leader Kim Jong-un has ordered the execution of his uncle's entire family, including his children and relatives serving as ambassadors to Cuba and Malaysia, according to South Korea's state news agency, Yonhap.

Jang Song-thaek, a once powerful North Korean military general, was executed last month as divisions between him and his nephew Kim widened.

All relatives of Jang have been put to death, including even children. Unnamed source for Yonhap.

Kim referred to Jang as "worse than a dog" and "human scum" in his announcement of his execution, which he said was for treachery and betreyal. Pictures showed Jang being led from his office by state security.

"Extensive executions have been carried out for relatives of Jang Song-thaek," an anonymous source said to Yonhap in a report published on Sunday. "All relatives of Jang have been put to death, including even children."

The executed relatives include Jang's sister Kye-sun, her husband and ambassador to Cuba, Jon Yong-jin, the ambassador to Malaysia, Jang Yong-chol, who is Jang's nephew, as well as his two sons, the sources said.

The two ambassadors were recalled to Pyongyang in early December. The sons, daughters and grandchildren of Jang's two brothers were all executed, the sources told Yonhap.

One source told Yonhap that some relatives were dragged out of their houses and shot in front of a crowd.

South Korea's state news agency did not specify when they were killed. The article does not mention any specific sources and the agency is known for its anti-North Korean bias.