Protesters hold a rally in Seoul, Jan. 4, calling for the immediate arrest of suspended President Yoon Suk Yeol. Yonhap

Tens of thousands of people gathered in Seoul, Saturday, to rally for or against the detention of President Yoon Suk Yeol following his short-lived imposition of martial law in early December, escalating tension and disrupting traffic.

Around 35,000 people staged pro-Yoon rallies near Gwanghwamun Square in central Seoul at 1 p.m., then suddenly moved to Hannam-dong in Yongsan District to stand against anti-Yoon protestors.

Just 400 meters away, members of the militant labor umbrella the Korean Confederation of Trade Unions (KCTU) held a rally calling for the immediate arrest of Yoon.

The KCTU members tried to march near Yoon's residence, which was blocked by police. Over the course, there were physical clashes and two people were detained for allegedly assaulting police officers.

Protesters from conservative groups attend a rally supporting suspended President Yoon Suk Yeol near Gwanghwamun Square in central Seoul, Jan. 4. Yonhap

Protesters occupied roads, which caused severe traffic congestion in the area. Seoul's Hangangjin Station was also briefly closed, with trains passing it without stopping.

Separately, a large-scale protest took place near Gwanghwamun Square demanding the swift impeachment of Yoon.

On Friday, the Corruption Investigation Office for High-ranking Officials (CIO) made a botched attempt to detain Yoon after a six-hour deadlock with Yoon's security team at the presidential residence compound.

Yoon's shocking, albeit short-lived, martial law declaration was followed by the National Assembly's impeachment vote pending a final ruling by the Constitutional Court.

An investigation is under way into the incident, but Yoon has refused to appear for questioning, leading to a court's issuance of a warrant for his detention. (Yonhap)