SEOUL (AFP) - A senior North Korean diplomat has scoffed at sensational rumours that the executed uncle of leader Kim Jong-Un was stripped naked and fed to a pack of starving dogs.

"No, no... he was shot to death," Hyun Hak-Bong, the communist nation's ambassador to Britain, told Sky News in an interview that aired Thursday.

Jang Song-Thaek, once the North's unofficial number two and Kim's political mentor, was put to death on December 12 on an array of charges including treason and corruption.

The story that Mr Kim had his elderly uncle fed naked to 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 shocked headlines in the Western media. As well as ravenous dogs, other reported methods of execution in North Korea have included flamethrowers and mortar shells.

The envoy said Jang was executed because he "abused his power" in hindering efforts to improve North Korea's economy and living standards.

Jang had personally spent 4.6 million euros (S$8 million) in 2009 alone and made "tremendous" crimes, Mr Hyun said.

Members of Jang's wider family, including children and grandchildren, have reportedly been executed along with his political supporters. The envoy retorted: "This is the political propaganda by our enemies. I think that fabricated report does not deserve my comment."

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

Jang's widow, the leader's aunt Kim Kyong-Hui, has not been seen in public since September. One report in a leading South Korean newspaper this month said that she may have already died - either of a heart attack or by suicide.

Jang's shock execution was the biggest political upheaval since the young ruler took power after the death of his father Kim Jong-Il in December 2011.