SEOUL (REUTERS) - South Korean President Moon Jae-in replaced his chief of staff, who played a key role in improving ties with North Korea, with a longtime confidant on Tuesday (Jan 8) as part of a shake-up aimed at raising approval ratings amid economic woes and a spy scandal.

Moon replaced Im Jong-seok with Noh Young-min, a former politician who has been serving as ambassador to China since October 2017, as the top presidential secretary, the Blue House said.

Yoon Do-han, a former journalist, was named press secretary, while former lawmaker Kang Gi-jung will be the senior secretary for political affairs, Moon's office said.

Noh and Kang worked on Moon's presidential campaign in the run-up to the 2017 snap election.

The three posts do not require confirmation hearings.

The reshuffle is seen aimed at revitalising momentum for an administration facing faltering approval ratings and the spying scandal which have both slowed Moon's legislative agenda.

The Blue House has been grappling with allegations that it has spied on political foes and officials from previous administrations while interfering in personnel management at private businesses.

Moon's office says the claims are groundless.

Among Moon's key tasks this year is boosting the economy and a sluggish job market and hosting North Korean leader Kim Jong Un on an unprecedented trip to Seoul.

Kim's visit was planned last year but delayed amid stalled nuclear talks between Pyongyang and Washington, in which Seoul played a bridging role. Kim also seeks a second summit with US President Donald Trump this year.

Moon's approval ratings have dropped to the lowest levels since he took office in May 2017 on the back of growing frustration over economic policies and lacklustre progress on North Korea's planned denuclearisation.

North and South Korea are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty, but relations have warmed significantly since the North sent a delegation to the Winter Olympics in the South last year.

Im, a former student democracy activist who served a three-and-a-half year prison term for orchestrating an unauthorised 1989 visit by a fellow campaigner to North Korea, played a pivotal role in the detente between the two Koreas.

The Blue House did not announce Im's next move, but he was widely expected to seek a return to politics through next year's parliamentary election.