SEOUL (AFP) - The aunt of North Korean leader Kim Jong-Un appeared to have returned home last month after receiving treatment abroad for heart disease, a report said on Friday.

The whereabouts and status of Kim Kyong-Hui have been a focus of media attention after her husband Jang Song-Thaek was executed last week in the biggest political upheaval since the young leader inherited power two years ago.

"To my knowledge, Kim Kyong-Hui had been receiving treatment for heart disease and returned to North Korea last month," a diplomatic source in Beijing told Yonhap news agency.

There was no indication of where she was treated but earlier reports have said she had sought treatment in Singapore on several occasions.

Jang's widow had been named by state media last week as attending an official function, suggesting she may have survived the purge of Jang associates.

But she apparently missed a crucial political event on Tuesday on the second anniversary of the death of her brother and former leader Kim Jong-Il.

Jang's execution raised questions about factional infighting at the top of the Pyongyang hierarchy and prompted both Seoul and Washington to warn of possible provocative acts by the nuclear-armed North.

Jang and his wife were once regarded as playing a key role in bolstering the leadership of the young and inexperienced leader.

But Kim Kyong-Hui, 67, has been less visible in the past year, with reports saying she was seriously ill.