Seoul, South Korea - South Korea's suspended president, Yoon Suk Yeol, has for the third time in a row failed to heed a summons to appear before the country's law enforcement authorities, the Yonhap news agency reported on Sunday.

The Corruption Investigation Office said that Yoon had failed to appear at their offices south of Seoul when summonsed, Yonhap reported.

Yoon had ignored previous summonses on December 18 and 25.

The likelihood was rising that office would issue an arrest warrant against Yoon, Yonhap said.

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The corruption office is investigating Yoon for unexpectedly imposing martial law on December 3, before lifting the declaration hours later.

South Korea has been in political crisis ever since. The National Assembly voted to impeach Yoon on December 14, and the Constitutional Court has launched the relevant proceedings to take a final decision on whether the assembly's vote is constitutional or not.

Yoon recently defended his controversial decision to impose martial law by saying he was acting to protect the nation. The opposition accuses him of violating the constitution.