TOKYO (Yonhap) -- North Korean leader Kim Jong-un's aunt is staying in Europe following the execution of her husband, Jang Song-thaek, a news report said Thursday.

Kim Kyong-hui, a senior party secretary and sister of late North Korean leader Kim Jong-il, stayed in Switzerland after the North executed Jang in December on charges of treason, Japan's Yomiuri Shimbun reported, citing unidentified sources.

The newspaper also said it obtained information that she later moved to Poland where Kim Pyong-il, the half-brother of late leader Kim Jong-il, has been serving as the North's top envoy since 1998. Kim Jong-il was the father of current leader Kim.

Kim Kyong-hui was last seen in public on Sept. 9 when she watched a military performance.

South Korean officials said earlier this month that Kim Kyong-hui appeared to be in gravely poor health.