Kim Kyong Hui at a meeting of the Workers' Party of Korea in 2010.

Kim Jong Un's aunt has died less than a month after her husband was executed by the North Korean dictator, according to reports from the secretive state.

Kim Kyong Hui, 67, either died of a heart attack or committed suicide, North Korean media reported.

Her husband Jang Song Thaek, described as "womanising scum" by his nephew, was executed under Jong Un's orders on December 8 in what was believed to be an attempt to tighten his grip on North Korea.

first family: North Korea's founder Kim Il Sung (C), his son Kim Jong Il and daughter Kim Kyong Hui.

Kyong Hui, who had received treatment for heart disease, was said to have had a heart attack soon after her husband was killed.

She also reportedly suffered from alcoholism and depression following the death of her only child who committed suicide in Paris in 2006.

North Korean intelligence services believed Kyong Hui to be dead but had not confirmed how or where she had died, South Korean newspaper the Chosunilbo said.

Toshimitsu Shigemura, a professor at Tokyo's Waseda University and an authority on North Korean affairs, said given her history of ill health, he would not be surprised if Kyong Hui was dead.

"'No one could go against her and she could force the party and the military to obey her orders by invoking her father's name.

'Her disappearance will inevitably cause a lot of political problems in Pyongyang. Kim Jong Un may be trying to cover her disappearance up for a while to consolidate his own political strength."

Kyong Hui has not been seen in public since September 10, when she attended a concert with Jong Un and his wife.

After the sudden death of Kim's father in December 2011, Jang acted as regent to his young nephew as Kim established himself in power. He become one of the most powerful men in the country.

He made the headlines again last week, when a report emerged claiming he had been feed to a pack of dogs by Kim.

The story, which spread like wildfire after it was picked up by a Hong Kong-based newspaper, appeared to have originated as satire on Chinese microblogging website, Tencent Weibo.