SEOUL, Jan 21 (Reuters): A South Korean court jailed former Prime Minister Han Duck-soo for 23 years on Wednesday, on charges that included insurrection relating to ex-President Yoon Suk Yeol's declaration of martial law in December 2024.

Han, 76, is the first former cabinet minister to be handed a ruling by a court on criminal charges directly related to martial law, which legal experts have said could prove a bellwether for other trials.

The Seoul Central District Court found Han guilty because he was instrumental in setting up the outward appearance of a cabinet meeting that facilitated the declaration, a judge said, a move he described as a "top-down insurrection". Han also discussed plans to block the function of major institutions such as parliament as part of the insurrection, the judge added.

"The defendant was a prime minister who had been indirectly given democratic legitimacy and responsibility ... Nevertheless, the defendant chose to turn a blind eye ... and participate as a member of the December 3 insurrection," the judge said. "As a result, South Korea was in danger of returning to the dark past when the basic rights and liberal democratic order of the people were violated, potentially preventing them from escaping ... dictatorship for a long time."

The court found Han guilty of "engaging in (the) key action of insurrection", as well as on related charges of perjury and falsifying an official document. "I will humbly follow the judge's decision," Han, clad in a suit and green tie, said after the ruling.

He had denied wrongdoing on all charges except perjury, saying in November that while he regretted not being able to stop Yoon from declaring martial law, he "never agreed to it or tried to help". In an unusual instance in South Korean court proceedings, the 23-year term exceeded a sentence of 15 years sought by prosecutors in November.

Han was detained by the court immediately after the ruling, which can be appealed. Han's lawyer said it would be taken to the Supreme Court. "This ruling is something that citizens who oppose martial law can fully accept," 23-year-old Kim Su-hyeon, a commuter watching the news on television at a train station, told Reuters.