SEOUL -- South Korean National Assembly Speaker Woo Won-shik said Sunday it would be a "blatant violation of the Constitution" should the prime minister and ruling party jointly exercise presidential power.

Woo made the remarks during a press conference at the National Assembly, just hours after Prime Minister Han Duck-soo and ruling People Power Party leader Han Dong-hoon issued a joint statement, affirming President Yoon Suk-yeol would not be involved in the country's internal and foreign affairs before he steps down.

Woo said that presenting the joint statement is an act of misleading the public as it makes an unconstitutional act look legitimate, calling it "arrogant."

"The transfer of presidential power comes from the people, and such a process should abide by the Constitution and the principle of popular sovereignty," Woo said, adding "Impeachment is the only legal procedure to suspend the president from carrying out his duties."

The parliament speaker also proposed talks between the ruling party and the main opposition to discuss the immediate suspension of Yoon's duties and resolve the political turmoil following Yoon's short-lived declaration of martial law Tuesday.

In a further development Sunday, President Yoon accepted the resignation of Minister of the Interior and Safety Lee Sang-min.

"I believe stepping down is necessary to prevent further disruptions and confusion in governance," Lee said in a statement.

Lee's resignation followed an impeachment motion filed by the main opposition Democratic Party of Korea on Saturday, which accused him of complicity in the declaration of martial law and mobilizing police to block lawmakers from entering the National Assembly.