SEOUL - South Korea's Constitutional Court overturned on Thursday parliament's impeachment of Justice Minister Park Sung-jae for his involvement in the December 3 martial law declaration by ousted President Yoon Suk-yeol, a court official said.

Park was impeached in December by parliament, after being accused of aiding Yoon when the then president briefly imposed martial law, an action that triggered the country's worst political crisis in decades.

The court ruled to remove Yoon from office last week saying he violated his duty as president by declaring martial law without just grounds and acted beyond his constitutional powers inflicting "a serious challenge to democracy."

Park and Prime Minister Han Duck-soo were the two cabinet members to be impeached, although both denied supporting Yoon's actions.

Han was reinstated in late March and resumed his role as acting president. He will continue in the post until a new presidential election is held on June 3.

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Park said the court vindicated him because "I had done nothing wrong to be impeached," as he returned to office after the ruling.

Two other cabinet ministers, accused of playing more active roles, resigned before parliament could bring motions to impeach them.

The defence minister at the time, Kim Yong-hyun, who is accused of recommending Yoon declare martial law, is on criminal trial on insurrection charges.

In the end, the martial law only lasted about six hours after lawmakers defied a security cordon around parliament and voted to reject the declaration.

Yoon, who is separately on trial over criminal charges of leading an insurrection, has not been seen in public since the April 4 ruling ousting him.

He was preparing to move back to his private residence from the official presidential compound soon, media reports said.