Morse Tan, a Korean American professor facing allegations of defaming President Lee Jae Myung, speaks to protesters demonstrating against ballot shortages in the June 3 local elections outside SK Olympic Park Handball Gymnasium in southern Seoul, Wednesday. Yonhap

Morse Tan, a Korean American professor at U.S.-based Liberty University, has been questioned by police over his alleged defamation of President Lee Jae Myung, his lawyers said Friday.

The U.S. professor underwent a two-hour private questioning session Thursday, according to his lawyers.

Tan is accused of falsely claiming at a press conference in the United States last year that Lee was involved in murder as a teenager and had been sent to a juvenile detention center for the crime.

"We believe further questioning to be highly unlikely," the lawyers said in a notice to the press.