A television at a train station in Seoul live broadcasts the verdict of South Korean former president Yoon Suk-yeol's case on Friday. YONHAP

South Korea's former president Yoon Suk-yeol was sentenced on Friday to five years in prison in a case related to his failed martial law bid in late 2024, marking the first verdict in eight cases he is facing.

The ruling was handed down by the Seoul Central District Court. The charges include obstructing an arrest attempt by investigators, abuse of authority, and other crimes, according to Yonhap News Agency.

In the hearing attended by the jailed former leader, Judge Baek Dae-hyun said the court found Yoon guilty of the charges of mobilizing staff from the presidential security service on Jan 3 last year to obstruct the arrest attempt by the Corruption Investigation Office for High-ranking Officials.

He was also convicted of infringing on ministers' constitutional right to deliberate on the martial law decree, as well as fabricating and destroying documents.

"Given the circumstances leading to the crimes, the specific details of the offenses, the nature of the crime is extremely bad," said Baek, adding that Yoon has shown no sign of remorse for his actions.

On Dec 3, 2024, Yoon declared martial law, claiming the move was to protect the country from "anti-state" forces that included the then-opposition Democratic Party and its lawmakers in the National Assembly.

However, the martial law decree lasted only about six hours as the National Assembly voted to revoke it. Yoon was later impeached and removed from office by the constitutional court in April.

The special counsel team, led by Cho Eun-suk, initially requested the court to sentence Yoon to 10 years in prison last month.

The hearing session was televised live, marking the third public live broadcast of a former president's sentencing trial, following those of former top leaders Park Geun-hye and Lee Myung-bak.

Yoon's legal team said they will appeal the verdict as they believe the ruling contains significant legal errors that must be re-examined in a higher court.

"We express strong regret that the decision was politicized," Yoo Jung-hwa, one of Yoon's lawyers, told reporters outside the court.

Jung Chung-rae, leader of the ruling Democratic Party, said the eradication of insurrection has just begun.

"We cannot stop at the first step," Jung said in a social media post after the court's ruling. "From five years to the death penalty, even the lightest remnants of the rebellion must be punished with zero tolerance."

South Korea's special counsel demanded on Tuesday the death penalty for the former president on charges of insurrection. The court's ruling on that matter is scheduled for Feb 19.

Park Sung-hoon, senior spokesman for the main opposition People Power Party, said it has no comment on the court's decision as Yoon has already left the party.

He said the party expects a fair and neutral trial in the future.

At a news conference on Jan 7, party leader Jang Dong-hyeok apologized for Yoon's martial law declaration, saying it was "the wrong measure", The Korea Herald newspaper reported.