SEOUL, South Korea — The South Korean government on Monday ordered an overseas travel ban on President Yoon Suk Yeol as he faces investigation on possible rebellion charges over a short-lived martial law declaration that plunged the key U.S. ally into chaos last week.

Opposition lawmakers are continuing to pursue impeachment for Yoon, 63, who stunned the East Asian democracy on Tuesday when he declared emergency martial law, accusing the opposition-controlled parliament of paralyzing the…