Videos widely shared on X showed several members of Yoon's security detail muzzling and removing the man, who appeared to be a student, from the ceremony at the Korea Advanced Institute of Science & Technology (KAIST).

The man could be heard protesting against cuts to the research and development budget under the Yoon administration as the president was making vows to support researchers.

"The Presidential Security Service removed a heckler to ensure safety within a security area and order in the venue," a spokesperson for Yoon's office said in a statement.

The action was "inevitable" and in accordance with the law, and security principles, the spokesperson added.

Keywords such as "KAIST graduation ceremony" and "budget cuts" were trending on X in South Korea on Friday, and the incident drew criticism from opposition politicians and several ordinary Koreans.

"Apologize, President," South Korea's main opposition party leader, Lee Jae-myung, wrote in a post on X.

South Korea's National Assembly passed a national research and development budget of 26.5 trillion won ($19.86 billion) in December for 2024, down 15% from the previous year, drawing backlash from researchers and students.

Minor progressive Jinbo Party lawmaker Kang Sung-hee was also dragged out of a venue by Yoon's bodyguards last month at an event the president was attending.

Kang was shouting and not letting go of the president's hand, an official at Yoon's office said at that time.

($1 = 1,334.3700 won)

(Reporting by Hyunsu Yim; editing by Miral Fahmy)