SEOUL • North Korean leader Kim Jong Un's 21-year-old nephew has been expressing increasing frustration about his life on the run and has begun to develop a habit of daytime drinking, South Korean media has reported.

Mr Kim Han Sol, along with his mother Ri Hye Kyong and his 19-year-old sister Kim Sol Hui, has been in hiding from the North Korean regime after his father Kim Jong Nam was killed at a Malaysian airport in February.

Mr Kim Jong Nam, who was the half brother of the North Korean strongman, was murdered with the banned VX nerve agent in broad daylight while waiting for his flight to Macau.

"According to various sources, Kim Han Sol is under 'iron-like' protection at his mother's house. This keeps him safe, but also makes him frustrated," TV Chosun, a media outlet in Seoul, said on Monday.

"He has been telling the people around him that he is glad his family is safe, but the protection programme is suffocating. He has also been consuming alcohol, often during the daytime, while saying that he had more freedom working in Macau," the report said.

Mr Kim Han Sol and the rest of the family were reportedly residing in Macau at the time of his father's murder, and had worked as an employee at a nearby hotel there. The family had been living a life of exile from North Korea since 2001.

The trio's current whereabouts are unknown, although the respective governments of the Netherlands, China, the United States and a fourth unnamed nation had offered help to them, according to Cheollima Civil Defence, an organisation which is keeping the family under Pyongyang's radar. The group is believed to comprise North Korean dissidents.

The Wall Street Journal earlier this month cited an unnamed Cheollima source as saying the North Korean regime may be targeting Mr Kim Han Sol, and that there were "attempts by several parties to interfere" with the family's evacuation from Macau.

Mr Kim Han Sol is believed to be the last surviving male of "Baekdu" descent, the direct bloodline of North Korean state founder Kim Il Sung and Kim Jong Il, which could make him a potential threat to his uncle Kim Jong Un.

THE KOREA HERALD/ASIA NEWS NETWORK