The younger sister of North Korean leader Kim Jong-un has been assisting her brother as his chief of staff since last year, a source familiar with North Korean affairs said Sunday.

Kim Yo-jung, 27, was appointed chief secretary of the ruling Workers' Party in the first half of last year, a post equivalent to South Korea's presidential chief of staff, the source said, asking that he not be identified.

The chief secretary does not take part in policy decisions but is in charge of purchasing and providing daily necessities to the leader and his family.

He or she also handles the delivery of official reports from the party, the Cabinet, the powerful National Defense Commission and other key state organizations to the top leader.

Before the younger Kim's promotion, the leader's first chief secretary was Kim Chang-son, who is now known to serve as chief of protocol.

"(Kim Yo-jung) was probably trained as she worked under Kim Chang-son," the source said.

In North Korea's dynastic regime, the powerful job has always been held by a close aide to the leader. Kim Yo-jung is the first family member to hold the post. The move is seen as an attempt by the Kim Jong-un regime to consolidate power following the country's execution of his once-powerful uncle, Jang Song-thaek, last December.

Kim Yo-jung received the media spotlight for accompanying her elder brother when he cast his ballot in the elections for the country's rubber-stamp parliament on March 9.

The younger Kim was listed among senior officials of the Central Committee of the Workers' Party, though she was not elected to the one-house legislature, called the Supreme People's Assembly.(Yonhap)