A South Korean joint investigation team, including police, has issued a summons to impeached President Yoon Suk-yeol to appear for questioning next week.

It's the second time the joint team has made the request. It also did so on Wednesday.

The team announced on Friday that it sent the summons via express mail and electronically to Yoon to appear for questioning at the Corruption Investigation Office for High-ranking Officials, or CIO, at 10 a.m. next Wednesday.

Yonhap News Agency said the team is looking at charges of insurrection and abuse of power against Yoon.

The news agency also said the CIO plans to consider filing for a court warrant to detain Yoon if he continues to ignore the summons without valid grounds.

The investigation team also said on Friday that they had questioned Prime Minister Han Duck-soo and eight others who had attended a Cabinet meeting Yoon held shortly before he declared martial law early this month.

Han, who concurrently serves as acting president, had told the National Assembly last week that all the Cabinet members who were present at the meeting opposed Yoon's martial law declaration.

The team is accelerating their probe and considering questioning Cabinet members and others again.