President Yoon Suk Yeol (right) and first lady Kim Keon Hee salute the national flag as they met overseas Koreans in Honolulu, Hawaii on Monday. (Yonhap)

The Legislation and Judiciary Committee at the National Assembly approved a plan to hold two rounds of hearings later this month on the online petition on the parliament's website calling for the impeachment of President Yoon Suk Yeol. The committee, controlled by the main opposition Democratic Party of Korea, also decided to summon Yoon's wife, Kim Keon Hee, to testify before the National Assembly on July 26.

This is the first time in modern Korean history that the parliament has summoned a first lady as a witness.

The decision was made as the ruling People Power Party's lawmakers walked out in protest.

The committee pointed to Kim's alleged antigraft law violation through the acceptance of a luxury Dior bag valued at 3 million won ($2,169) last year, and her alleged involvement in stock price manipulation from approximately the early 2010s, as the unidentified author of the petition picked the Yoon family's "corruption" as one of the reasons why Yoon deserves impeachment.

The petition, posted on June 20, had collected over 1.3 million signatures as of Tuesday. Legislative steps must be taken to petitions on the National Assembly website that have received at least 50,000 signatures within a month.

First lady Kim Keon Hee arrives in Honolulu, Hawaii to accompany President Yoon Suk Yeol on his visit there on Monday. (Yonhap)

Kim, along with Yoon's mother-in-law, Choi Eun-soon, will be among 39 witnesses to be summoned later in July.

Witnesses who refuse to attend the hearing for testimony without justifiable grounds may face up to three years of imprisonment or a fine of at least 10 million won ($7,240) but no more than 30 million won.

The presidential office was not immediately available for comment as of press time.

Kim arrived Monday in Honolulu, Hawaii accompanying President Yoon Suk Yeol on his trip to the United States to visit the US Indo-Pacific Command in Honolulu and attend the North Atlantic Treaty Organization in Washington.