South Korea's impeached President Yoon Suk Yeol refused to be questioned by investigators on Monday under a probe into whether he committed insurrection, as dozens of his supporters faced being charged over a violent rampage on a court building.

SEOUL (Reuters) - A South Korean court granted on Sunday an extension of President Yoon Suk Yeol's detention, saying there was "concern" that Yoon could "destroy evidence" in a criminal probe related to his short-lived declaration of martial law in early December.

Since police broke up a crowd of Yoon's supporters blocking the court gate in the morning, thousands of supporters surrounded the court after the hearing began at around 2 p.m. (0500 GMT) behind a police barricade chanting "release the president".