SEOUL (Reuters) -South Korea's acting president faces an impeachment vote on Friday, intensifying a political crisis as the Constitutional Court meets for its first hearing on suspended President Yoon Suk Yeol's short-lived martial law declared on Dec. 3.

The lawyers for a former South Korean defence minister under investigation on insurrection charges said on Thursday a short-lived martial law decree imposed earlier this month was to raise alarm on opposition parties' abuse of the democratic process.

South Korea’s President Yoon Suk Yeol again declined to appear for questioning by investigators over his martial law declaration as the embattled leader seeks to first defend himself at an impeachment trial.