Former South Korean Prime Minister Han Duck-soo was summoned Wednesday along with Industry Minister Ahn Duk-geun by a special prosecutor investigating ex-President Yoon Suk Yeol's failed bid to impose martial law last year, according to local media reports.

Special counsel Cho Eun-suk has been checking whether Yoon abused his power or some Cabinet ministers cooperated with him in his botched martial law bid on Dec. 3, Yonhap News Agency reported.

Both Han and Ahn appeared before the special prosecutor but avoided speaking with reporters upon entering the special counsel's office.

Yoon appeared last Saturday for questioning before a special prosecutor on insurrection charges related to his martial law declaration and his lawyers said he will again appear before the special prosecutor this Saturday.

Yoon was ousted from office in April by the Constitutional Court for his failed bid to impose martial law.

He was arrested and indicted for abuse of power and leading an insurrection in January, making him the first sitting president to be held in custody in South Korea’s history.

He was released from prison in March after a district court canceled his arrest warrant and allowed him to stand trial without being physically detained.