South Korean President Yoon Suk Yeol was ousted by the Constitutional Court on Friday, which upheld parliament's impeachment motion over his short-lived imposition of martial law last year that sparked the country's worst political crisis in decades.With Yoon's ouster, a presidential election is required to take place within 60 days, according to the country's constitution.

Prime Minister Han Duck-soo will continue to serve as acting president until the new president is inaugurated.

Acting Chief Justice Moon Hyung-bae said violated his duty as president by taking actions that were beyond the powers given to him under the Constitution, and the effect of his actions was a serious challenge to democracy.

"(Yoon) committed a grave betrayal of the people's trust who are the sovereign members of the democratic republic," he said, adding by declaring martial law Yoon, created chaos in all areas of society, the economy, foreign policy.

The ruling was unanimous among the eight justices, Moon said.

Thousands of people at a rally calling for Yoon's ouster, including hundreds who had camped out overnight, erupted into wild cheers on hearing the ruling, chanting "We won!"

The ruling caps months of political turmoil that have overshadowed efforts to deal with the new administration of U.S. President Donald Trump at a time of slowing growth.

Separately, 64-year-old Yoon faces a criminal trial on insurrection charges. The embattled leader became the first sitting South Korean president to be arrested on January 15 but was released in March after a court cancelled his arrest warrant.

The crisis was triggered by Yoon's December 3 declaration of martial law, which he has said was needed to root out "anti-state" elements and the opposition Democratic Party's alleged abuse of its parliamentary majority that he said was destroying the country.

Yoon lifted the decree six hours later after lawmakers defied efforts by the security forces to seal off parliament and voted to reject it. Yoon has said he never intended to fully impose emergency military rule and tried to downplay the fallout, saying nobody was hurt.

Months of protests have followed, and it remained unclear if the political chaos sparked by Yoon's martial law declaration will now be eased by the court ruling.

(Reuters)

South Korea's President Yoon ousted by Constitutional Court