South Korea's ex-president indicted for abuse of power

South Korean ex-president Yoon Suk-yeol was indicted for abuse of power Saturday over his declaration of martial law last year, as investigators widened an insurrection probe.

Yoon plunged South Korea into a political crisis when he sought to subvert civilian rule on December 3, sending troops to parliament in a bid to prevent lawmakers voting down his declaration of martial law.

He became the first sitting president in the country to be taken into custody when he was detained in January after resisting arrest for weeks, using his presidential security detail to thwart investigators.

He was released on procedural grounds in March, even as his trial on insurrection charges continued.

Last week he was detained again after an arrest warrant was issued over concerns he might destroy evidence in the case.

The prosecution "indicted former President Yoon Suk-yeol on charges including abuse of power and obstruction of special official duties", prosecutor Park Ji-young told reporters Saturday.

Park said Yoon also did not follow the required procedure to declare martial law, including holding a meeting with all cabinet members of the government.

Yoon was also charged with "drafting and discarding a false document" that stated the prime minister and defense minister had endorsed martial law.

Yoon has refused to attend questioning since he was detained, but appeared in court on Friday at a hearing to argue for his warrant to be cancelled.

The ex-president's legal team told reporters that Yoon defended himself for over 30 minutes, and mentioned his "limited physical mobility and the challenges he was facing".

The court denied the request.

Yoon is being held in solitary in a cell which has a fan but no air-conditioning, as a heat wave grips South Korea.