SEOUL -- South Korea's main liberal opposition Democratic Party said Thursday that it planned to vote on an impeachment motion against President Yoon Suk-yeol on Saturday.

The party's deputy spokesperson told reporters that the vote would be held at around 7:00 pm local time on Saturday in a bid to allow lawmakers of the ruling People Power Party enough time to consider it.

The Democratic Party and five other minor parties submitted the motion to impeach Yoon Wednesday and reported it to the National Assembly's plenary session early Thursday as the opposition believed the president's martial law declaration was illegal and unconstitutional.

Yoon declared an emergency martial law Tuesday night before repealing it early Wednesday as the parliament voted against it.

Under the constitution, the impeachment bill must be initiated by a majority of lawmakers and approved by at least two-thirds of National Assembly legislators.

The opposition will need eight votes from 108 lawmakers of the ruling People Power Party to pass the motion.

If passed, it will be deliberated by the constitutional court for up to 180 days, during which Yoon's constitutional powers will be suspended, and Prime Minister Han Duck-soo will be an acting president.

If the impeachment of Yoon is upheld by the court, a new presidential election will be held within 60 days.