A senior North Korean diplomat derided sensational rumours that the executed uncle of leader Kim Jong-un was stripped naked and fed to starving dogs, AFP reported.

"He was shot to death," the communist nation's ambassador to Britain Hyun Hak-bong told Sky News.

Hyun stated that Jang Song-thaek was executed because he "abused his power" in impeding efforts to improve North Korea's economy and living standards.

Jang had personally spent 4.6 million euros (US$6.2 million) in 2009 alone and committed "tremendous" crimes, Hyun said.

Jang Song-thaek, once the North Korea's unofficial number two and Kim's political mentor, was sentenced to death on December 12, accused of plotting against the regime.

The story that Kim was executed by being devoured by ravenous dogs was apparently based on a satirical tweet posted on a Chinese website.

This was then picked up by a Hong Kong newspaper, leading to shocking headlines in the Western media.

The single-sourced report could not be independently verified and some experts questioned whether China was using the Beijing-controlled newspaper Wen Wei Po to spread anti-North Korea propaganda.

"The fact that it appeared in a Beijing-controlled newspaper showed that China no longer cares about its relations with the Kim regime," the Straits Times, a Singapore newspaper, reported.

South Korean news agency Yonhap recently claimed the entire family of purged military leader Jang Song-thaek has now been executed, and several children were killed in the purge.

The purge also allegedly claimed the life of Jang's sister Jang Kye-sun; Cuba ambassador Jon Yong-jin; and Malaysia ambassador Jang Yong-chol, who was a nephew of the general.

Some relatives by marriage have reportedly been spared and are believed to have been sent to remote villages.

"I think that fabricated report does not deserve my comment," Hyun said.

"This is the political propaganda by our enemies," he added.

Asked whether this means they are alive, Hyun said: "I know he was punished, but (if) his family were punished or not, I don't know."