Seoul, July 20 -- A day after South Korea's former President Yoon Suk Yeol was indicted on additional charges of abuse of power over his declaration of martial law last December, authorities on Sunday questioned the country's Unification Minister Kim Yung-ho.

State news agency Yonhap reported that Kim was summoned to the special counsel's office inside the Seoul High Prosecutors Office in southern Seoul to be questioned as a witness in the case involving Yoon's failed attempt to impose martial law.

The minister was one of five Cabinet members, including then Prime Minister Han Duck-soo and Foreign Minister Cho Tae-yul, called to the presidential office on Dec. 3, shortly before Yoon declared martial law, it said.

He has previously test...