SEOUL - South Korea's impeached President Yoon Suk-yeol on Sunday turned down the third summons request to call him in for questioning in an investigation into his botched martial law imposition, Yonhap news agency reported on Sunday, citing an investigation body.

The Corruption Investigation Office for High-ranking Officials (CIO) handling the case said Yoon did not appear at its office in Gwacheon, just south of Seoul, at 10 am local time on Sunday as requested, the report said.

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The CIO launched a joint investigation unit with the National Office of Investigation and the defense ministry's investigative headquarters to look into Yoon's insurrection and other charges.

This marks the third time the embattled president has snubbed the summons request by the joint investigation unit. Yoon rejected the previous calls to appear for questioning on Dec 18 and Dec 25, respectively.

Yoon's repeated refusal to the summons requests could prompt the CIO to file a court warrant for his arrest, as three summonses are typically considered as the maximum number before an investigative agency seeks an arrest warrant against a suspect, Yonhap said.

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Yoon was named by investigative agencies as a suspect on alleged insurrection charge following his declaration of an emergency martial law on the night of Dec 3, which was revoked by the National Assembly hours later.

He was impeached by the parliament earlier this month over his short-lived imposition of the martial law decree.