Former North Korean leader Kim Jong-il's fourth wife Kim Ok was purged and sent to a prison camp less than a year after her stepson Kim Jong-un took power, Radio Free Asia reported Tuesday.

A Chinese businessman who visited Pyongyang recently told the radio station he heard from a senior Workers Party official that Kim Ok (52) had been sent off to a camp for political prisoners with her parents and siblings.

The last straw was apparently the arrogant attitude of her younger brother Kim Kyun.

"Kim Kyun acted high-handedly and tyrannically as his sister was Kim Jong-il's favorite after Kim Jong-un's mother Ko Yong-hui died in 2004," RFA said.

Kim Kyun was appointed first vice president of Kim Il-sung University in February 2011 but abruptly resigned from his post in October 2013.

Quoting another source, RFA said Kim Ok was always bound to be purged after Kim Jong-un took power, given that Kim Jong-il also disappeared his father Kim Il-sung's second wife when the nation founder died in 1994.

Kim Jong-un had no reason to protect Kim Ok, who he may have felt took his mother’s place, a source said.

Kim Ok studied piano at Pyongyang University of Music and Dance and became a secretary to Kim Jong-il in 1980.

She was seen on several occasions with Kim Jong-un until October 2012 but then disappeared from the radar.

