North Korean leader Kim Jong-un has sacked the chief of the country's spy agency on suspected abuse of power after the ruling party conducted surveillance on the ministry, sources said Friday.

Kim Won-hong, 72, was dismissed from the head of the Ministry of State Security after the party's audit late last year found his agency had abused its authority, according to the sources familiar with North Korean affairs.

His military rank may have been demoted to lieutenant general from full general, they said.

North Korea's security ministry has powerful authority as it screens so-called reactionary elements in society, supervises political prisoners' camps and arrests those who attempt to flee the country.

Known as one of heavyweights in North Korea, Kim became the head of the spy agency in April 2012 after Kim Jong-un took office in late 2011.

He is also known to have spearheaded the move to execute Jang Song-thaek in December 2013, the once-powerful uncle of the North's young leader.

A local report said that Kim might have been dismissed for abusing his position and on corruption charges, adding there is a slim chance for him to be reinstated.

South Korea's intelligence agency said that it cannot confirm whether he was dismissed from his post.

North Korea's leader is believed to have executed more than 100 government and military officials as he seeks to consolidate his oppressive rule. (Yonhap)