South Korean President Yoon Suk Yeol has been banned from leaving the country over a failed attempt at imposing martial law, amid growing calls for him to step down and a deepening leadership crisis.

Yoon has apologised for the botched attempt and said he was leaving his political and legal fate to his ruling People Power Party (PPP) but has not resigned. 

He has become a subject of criminal investigation, according to local media reports.

On Monday, the defence ministry said Yoon was still legally commander in chief, but growing dissent among senior military officers against the president has thrown into question his grip on power.

Oh Dong-woon, the head of the Corruption Investigation Office for High-ranking Officials, said he had barred Yoon from foreign travel, when asked at a parliament hearing what actions have been taken against the president.