South Korean President Moon Jae-in threw the future of a significant reparations deal with Japan for so-called "comfort women" into doubt on Thursday, just two years after both countries declared it "final and irreversible."

Moon's announcement came a day after a state-appointed panel concluded that the previous South Korean government had failed to adequately communicate the proposed deal with the victims of wartime sex slavery before it struck an agreement with Japan.

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"It has been confirmed that the 2015 comfort women negotiation between South Korea had serious flaws, both in process and content," Moon's spokesman read out in a statement.

He added: "Despite the burden of the past agreement being a formal promise between governments that was ratified by the leaders of both countries, I, as president and with the Korean people, once again firmly state that this agreement does not resolve the issue over comfort women."

Korea, Japan displeased by progress

The panel found that the previous Seoul government had failed to make crucial elements of the deal public, including demands from Japan that agreement not include the term "sexual slavery" and that the South remove a bronze stature representing sex slaves from outside of its Seoul embassy.

The deal, reached in late 2015, centered on a formal apology from the Japanese government. It also included a 1 billion yen ($8.8 million, €7.4 million) payment to the dwindling number of surviving Korean victims forced to provide sex to Japanese soldiers during World War II. According to historians, Japan forced tens of thousands of Asian women, mainly from Korea, to work in front-line brothels.

Korea, in turn, said it would resolve Tokyo's grievances over the statue outside the Japanese embassy, which has not been removed.

Nuclear North keeps neighbors close

On Thursday, South Korea's Foreign Ministry said officials would begin talks with victims and experts before deciding whether to pursue changes to the deal. 

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However it remains unlikely that Seoul will escalate the issue into a major diplomatic row, with both countries pressed to rein in North Korea's nuclear weapons program.

Moon pledged on Thursday to maintain sound diplomatic relations with Japan and work toward "future-oriented cooperation."

dm/msh (AP, Reuters)