South Korean opposition lawmakers called for heightened security on Thursday after an MP was struck in the face with an egg outside a court, as police braced for potential unrest ahead of an anticipated ruling on the fate of the impeached president, Yoon Suk Yeol.

The controversy surrounding Yoon began after lawmakers suspended him over his disastrous declaration of martial law on December 3.

The Constitutional Court had held weeks of tense impeachment hearings last month, deliberating whether to formally remove him from office.

Despite experts predicting a verdict by mid-March, the court had not yet issued its final decision, making the case the longest deliberation in the court’s history.

While addressing reporters outside the court, opposition MP Back Hye-ryun, who had urged justices to uphold Yoon’s impeachment, was struck by at least one raw egg.

Police later confirmed that bananas had also been thrown during the incident. Although the attacker remained unidentified, authorities pointed to supporters of Yoon, who were reportedly staging a protest in the area at the time.

"In light of the gravity of the case, we have formed an investigation task force," said the Seoul Metropolitan Police Agency in a statement.

Following the incident, opposition lawmakers visited the National Police Agency, urging the police to bolster security around the court. A police report seen by AFP indicated that authorities had planned to deploy "100 percent of available personnel" and mobilise "all available equipment" on the day of the verdict.

The police force also stated that about 14,000 officers from 210 riot police units, more than half of the entire national riot police force, would be stationed in Seoul.

"Plainclothes officers will be positioned inside the Constitutional Court, while police special forces will remain on standby in surrounding areas," the report added.

Additionally, the police had restricted access to 22 rooftops near the court, and the area had been designated a "no-fly zone" with anti-drone measures in place.

The country’s acting police chief had previously announced that the area around the court would be declared a "protest-free zone."

Officers were also undergoing additional training in the use of pepper spray and batons, with special units on standby to respond to potential bomb threats.

Yoon, who was detained in a dawn raid in January on charges of insurrection for declaring martial law, was released in early March on procedural grounds.

His supporters, meanwhile, had staged protests every weekend, with tens of thousands demanding the court reinstate him. Yoon’s release appeared to invigorate his backers, heightening tensions in the lead-up to the ruling.