A lawyer close to South Korean President Yoon Suk-yeol says the president is unlikely to appear for questioning on Wednesday as requested by a joint investigation team of authorities.

The investigation team, including police, is seeking to question Yoon on charges of insurrection and abuse of power. It sent its second summons requesting Yoon's appearance for questioning at 10 a.m. on Wednesday.

The lawyer, who has been acquainted with Yoon for 40 years and is involved in the selection of the president's defense team, spoke to reporters on Tuesday.

He said it seems unlikely that Yoon will be able to attend on Wednesday. He cited as the reason the fact that certain conditions had not been met.

The lawyer also said Yoon places priority on the Constitutional Court's impeachment trial proceedings, which are expected to start on Friday.

Yoon did not comply with the joint investigation team's first summons requesting him to appear for questioning on December 18.

South Korean media say the team plans to consider filing for a court warrant to detain Yoon if he fails to comply with the latest summons.