Former North Korean leader Kim Jong-il's widow appears to have fallen victim to a purge by the new regime, Radio Free Asia said on Tuesday.

Kim Ok and her father Kim Hyo, a senior official in the Workers Party's Finance and Accounting Department, "has recently been dismissed from all their posts," RFA quoted an informed source as saying. "They may have fallen victim to a political purge."

The defector-run radio station speculated that young leader Kim Jong-un has sacked his stepmother to tighten his own grip on power.

"Rumors are circulating in the North that the regime has forced all the old guard from the Kim Jong-il era to retire," another source said. "Kim Ok may be part of that move."

Right after he took power, Kim Jong-un attempted to purge the powerful military elite from the Kim Jong-il era, getting rid of army chief Ri Yong-ho and first deputy director of the State Security Department U Dong-chuk.

There have also been rumors that Kim Ok attempted suicide twice in early 2012, right after Kim Jong-il died. In July she defied doubters by accompanying Kim Jong-un on a tour of a new amusement park in Pyongyang, but since then she has disappeared from public view.

Media reports said she was seen receiving hospital treatment in Beijing and Berlin.