All relatives of the executed uncle of North Korean leader Kim Jong-un, including children and the country's ambassadors to Cuba and Malaysia, have also been put to death at the leader's instruction, Seoul's Yonhap news agency quoted multiple sources as saying Sunday.

Jang Song-thaek, the once-powerful uncle, was executed last month on charges of attempting to overthrow the regime, including contemplating a military-backed coup. All direct relatives of Jang have also been executed, the sources said.

"Extensive executions have been carried out for relatives of Jang Song-thaek," one source said on condition of anonymity. "All relatives of Jang have been put to death, including even children."

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

All of them were recalled to Pyongyang in early December and executed, they said. The sons, daughters and even grandchildren of Jang's two brothers were all executed, they said.

It was unclear exactly when they were killed, but they are believed to have been put to death after Jang's death on Dec. 12.

"Some relatives were shot to death by pistol in front of other people if they resisted while being dragged out of their apartment homes," another source said.

Some relatives by marriage, including the wife of the ambassador to Malaysia, have been spared from executions and sent to remote villages along with their maiden families, according to the sources.

"The executions of Jang's relatives mean that no traces of him should be left," a source said. "The purge of the Jang Song-thaek people is under way on an extensive scale from relatives and low-level officials."

(Agencies)