President Yoon Suk Yeol’s use of the expression “anti-state forces” in an apparent jab at the former Moon Jae-in administration sparked backlash from the liberal opposition and civic groups on Thursday.

The presidential office later the same day attempted to quell controversy, claiming the leader's "anti-state" reference was not directed at the previous administration.

Yoon made the remarks during a congratulatory speech at a ceremony to mark the founding anniversary of the Korea Freedom Federation, a conservative civic group, held in Jangchung Municipal Stadium in Seoul on Wednesday.

“Anti-state forces with a distorted sense of history and irresponsible view of the state implored for lifting of the United Nations Security Council sanctions against North Korea … and chanted for a declaration to end the Korean War, which would disband the United Nations Command.

"It was a hollow call for fake peace that said we should believe in the good intentions of the enemy that is seeking to invade us,” he said.

His words were widely seen as an attack on former President Moon, who looked to continue the pro-engagement legacy of South Korea’s center-left political faction and sought to break away from his predecessors' sanctions-oriented approach toward the North.

The liberal former leader persistently advocated for an end-of-war declaration, as the 1950-53 Korean War ended in a truce, not a peace treaty, meaning the two sides are technically still at war.

Although the Moon administration said it would merely be a political declaration that is not legally binding, there were concerns in both Seoul and Washington that should Pyongyang continue to demand the disbandment of the UNC, the end-of-war declaration could weaken the cause for maintaining it.

In Wednesday’s speech, Yoon also said there are so many groups that are “shaking and threatening” the country through instigation based on falsehood, fabrication and fake news.

The main opposition Democratic Party of Korea and several civic groups have been protesting Japan’s plan to discharge contaminated wastewater from the now-destroyed Fukushima Nuclear Power Plant into the sea, saying it would pose health risks to people in South Korea. Damaged by a massive earthquake and subsequent tsunami in 2011, the Fukushima plant stores over 1.3 million tons of water treated by a purification system.

Yoon was the first incumbent South Korean president to attend the founding anniversary ceremony of the KFF since Kim Dae-jung in 1999.

The opposition Democratic Party fumed at Yoon’s remarks, contending that the president had “insulted” his predecessor using “vulgar” language.

A group of opposition lawmakers, including Rep. Youn Kun-young, called for an official apology from Yoon.

“A person with such a simplistic perception that categorizes those with different ideas as ‘enemies’ cannot govern for the entire people of South Korea,” they said in a joint statement.

Yoo In-tae, former secretary-general of the National Assembly, pointed out in a radio interview on Thursday that Yoon himself held a key position in the Moon administration.

"Why did he go work as the prosecutor general for 'anti-state forces'?” Yoo said in reference to the president's previous position under Moon.

"He crossed the line. It feels like he is increasingly being controlled by the far right."

Yoon served as the head of the state prosecution until March 2021, and declared his presidential candidacy months later, eventually winning on the ticket of the conservative People Power Party.