South Korea's ousted premier said on Thursday that he had opposed suspended President Yoon Suk Yeol's declaration of martial law, testifying for the first time at his former boss's impeachment trial about the events of a night that threw the country into turmoil.

South Korean police raided the home and offices of former Interior Minister Lee Sang-min on Tuesday over his alleged role in President Yoon Suk Yeol's short-lived imposition of martial law, according to media reports.

Ousted South Korean leader Yoon Suk Yeol's bid to impose martial law was aimed at thwarting a "legislative dictatorship" by the opposition-controlledparliament, his lawyer said Thursday, as Yoon became the country's first sitting president to stand trial in a criminal case.