Kim Jong-un's purge continues as South Korean spies reveal 15 senior officials executed this year alone for challenging leader's authority

The North Korean leader has slowly been removing a number of key members of his father’s government since coming to power in 2011

Kim Jong-un is believed to have ordered the execution of 15 senior officials this year (KCNA)

Kim Jong-un is believed to have executed 15 senior officials this year who were accused of challenging his authority.

The executions are believed to have been ordered by the leader over a number of separate alleged crimes, from espionage to questioning Kim’s policies, according to South Korea’s spy agency.

Lee Byoung, the head of the country’s National Intelligence Service, informed government official Shin Kyoung Min that in January, a North Korean official with a rank comparable to a vice Cabinet minister in the South, was executed for questioning Kim’s policies on forestation.

Shin said another official of similar rank was executed in February for hesitating over plans laid out by Kim for the construction of a new building to be created in the shape of a flower named after the founder of North Korea, Kim Il Sung.

He added that the agency also believes North Korea used a firing squad in March to execute four senior members of Pyongyang's famous Unhasu Orchestra on charges of espionage, which Lee did not detail.

Shin said Lee did not reveal how the intelligence agency obtained the information, and the agency declined to confirm the comments when contacted by The Associated Press.

Kim Jong-un has had a number of key members of his father's old guard executed in a series of purges since 2011 (AFP)

Lee is also understood to have informed officials during a closed door meeting that Kim is expected to be visiting Russia next month for celebrations marking the 70s anniversary of its victory over Nazi Germany.

Since the death of Kim Jong-Il in 2011, Kim Jong-un has been removing key members of his father’s old guard, most notably in 2011 when he ordered the death of his uncle for alleged treason. Jang Song Thaek had at one point been considered the second most powerful person in North Korea and had been married to Kim Jong-Il’s sister.

Last year spy agency reported the government publicly executed at least 50 people, including several party officials. Many of those who died are believed to have been executed for watching soap operas and foreign broadcasts, which is banned in the country.

But a professor at the Seoul-based University of North Korean Studies told the Associated Press said these purges underline Kim Jong-un’s inexperience as a leader.

Yang Moo-Jin said these actions are those of a young dictator struggling to find effective ways to control his regime.

Additional reporting by Associated Press