A North Korean defector claims North Korean leader Kim Jong-un's aunt Kim Kyong-hui died of a stroke during a heated argument with her nephew over the execution of her husband Jang Song-thek .

CNN reports that Kang Myung-do, a defector and now a professor of Kyungmin University, said Kim Kyong-hui suffered the stroke while she was arguing on the phone with Kim Jong-un a matter of days after Jang's execution.

The defector says she was taken to hospital but later died.

North Korea experts say the claims could be true but are almost impossible to confirm.

Kim Kyung-hui has not been seen in public since Jang's execution late last year, sparking rumors of ill health or possible death.