The confirmation of Kim Yeon-chul as the new unification minister comes days before Moon flies to Washington for a summit with President Donald Trump as he seeks to rekindle dialogue between the US and North Korea after a failed summit in Hanoi in February.

The dovish South Korean president brokered the talks process between Trump and North Korean leader Kim Jong Un, which led to their first landmark summit in Singapore last June.

But at times security allies Seoul and Washington have appeared to diverge on their approach to Pyongyang, with Moon, a longstanding advocate of engagement with the North, regularly pushing inter-Korean cooperation projects.

Moon faced a heavy backlash last month after tapping Kim Yeon-chul, chief of the state-run Korea Institute of National Unification, to head the unification ministry which handles inter-Korean affairs.

Kim, also a vocal supporter of dialogue with Pyongyang and Moon's longtime confidante, has a record of challenging generally held views on highly emotive issues involving the North.

In a 2010 newspaper column, Kim wrote that the shooting dead of a South Korean tourist by a northern guard at the North's Mount Kumgang resort was a "rite of passage" that Seoul had to undergo in the early stages of cross-border cooperation.

All South Korean tours to the North were suspended following the 2008 killing.

Kim is also a vocal critic of sanctions against Pyongyang.

Shortly after Seoul's 2016 closure of the Kaesong Industrial Complex, where Southern firms used to be staffed by Northern workers, he told an interviewer that "sanctions and pressure was a failed approach".

Moon has been pushing for the resumption of both projects, but doing so would fall foul of the current sanctions system.

In spite of the collapse of the Hanoi summit, Moon said last month that Seoul would consult with the US on ways to resume South Korean tours to Mount Kumgang and restart operations at the joint factory park.

Moon is able to override opposition parties' strong objections to Kim's appointment as cabinet ministers do not require parliamentary approval.