A South Korean court ruling that ordered the Japanese government to pay damages to a group of former "comfort women" over their treatment in Japanese military brothels became final Saturday as a deadline for Tokyo to appeal expired.

The Japanese government had until Friday to appeal the first such ruling in South Korea, but it refused to participate in the case from the outset, citing sovereign immunity -- a principle under international law that allows a state to be shielded against the jurisdiction of foreign courts.

On Jan. 8, the Seoul Central District Court awarded 12 plaintiffs 100 million won ($90,400) each as demanded, saying the Japanese government committed "intentional, systematic and wide-ranging criminal acts against humanity."

The court also granted a provisional execution of the compensation order, making it possible to immediately seize Japanese government assets.

The ruling could worsen bilateral ties, which have sunk to the lowest point in decades following South Korean Supreme Court rulings in 2018 that ordered Japanese companies to compensate groups of South Koreans for forced labor during Japan's 1910-1945 colonial rule of the Korean Peninsula.

Japanese Prime Minister Yoshihide Suga has criticized the comfort women ruling as "totally unacceptable." Foreign Minister Toshimitsu Motegi is said to have told ruling party lawmakers this week that Japan will deal with the ruling by taking into account "every option."

Some Liberal Democratic Party lawmakers have requested Tokyo consider countermeasures against the ruling, including taking Seoul to the International Court of Justice.

Japan takes the position that all claims related to its colonial rule, including the issue of comfort women, were settled by a 1965 bilateral agreement under which it provided financial aid to Seoul with an understanding that the issue of compensation was resolved "completely and finally."

Kim Gang Won, a lawyer for the plaintiffs, has indicated that he sees no prospect of the damages ever being paid. "It is not easy to find assets owned by the Japanese government in South Korea that can be forcibly executed upon," he told Kyodo News.

Assets such as the Japanese Embassy in Seoul are difficult to seize because they are protected under a provision in the Vienna Convention on Diplomatic Relations that stipulates the premises of a diplomatic mission are inviolable.

On Friday, the new South Korean Ambassador to Japan Kang Chang Il said the two countries should discuss creating a new foundation using leftover funds from a previous foundation set up with money provided by Japan to help former comfort women.

Kang's proposal, told to reporters upon his arrival in Japan, came just days after President Moon Jae In said in a news conference that he felt "a bit perplexed" by the ruling.

The president himself has not indicated how South Korea as a government will deal with the ruling, but he acknowledged at the time that a deal struck by Seoul and Tokyo in 2015 to solve the issue of comfort women is an "official one between the governments" and that he will explore solutions based on the deal.

The two countries struck the deal to "finally and irreversibly" resolve the issue. As part of the agreement, the Japanese government paid 1 billion yen ($9.63 million), and the money was distributed through a foundation to former comfort women and the families of those who died.

However, the foundation was dissolved in 2019 after the Moon administration concluded that the deal, reached under a previous government, failed to properly reflect the women's wishes. Some 5.7 billion won remains unused.