Defector-turned-lawmaker Cho Myung-chul on Wednesday sued for defamation a university professor who called for the execution of North Korean escapees.

In a news briefing held at the National Assembly, Cho accused Yoon Jae-man, a Daegu University professor, of defamation and called his remarks in messenger app KakaoTalk "shocking." He said a complaint has been filed with the Seoul Central District Prosecutors' Office, calling for a probe into the matter.

The progressive scholar allegedly characterized North Korean defectors as being worse than collaborators with colonial Japan in the first half of the 20th century. He also said in the message posted Monday that just as France executed Nazi collaborators, defectors must be punished for wreaking havoc on South Korea's democracy. According to a conservative civic group that picked up the message, he further stated that defectors had aligned themselves with pro-Japanese elements in society.

"It is deplorable that Yoon called for the execution of defectors, and he must be held accountable for following the stance of Pyongyang in regards to people who escaped from the North," the first-term legislator said. The North frequently refers to defectors as traitors of the state and has called for their punishment.

Cho said the law professor should apologize immediately and take responsibility for his words.

"Yoon insulted all defectors," the Saenuri Party lawmaker said.(Yonhap News)