South Korea's first lady Kim Keon Hee is likely to refuse to testify before the opposition-controlled Legislation and Judiciary Committee of the National Assembly as they plan to hold a parliamentary hearing to seek an impeachment motion against President Yoon Suk Yeol.

This will be in line with the presidential office's move to decline to receive the committee's written request urging five presidential secretaries to attend the first round of hearings scheduled on Friday.

A senior official of the presidential office said on condition of anonymity that anyone in the presidential office "cannot (receive the request to) testify at the parliamentary hearing for (Yoon's) impeachment, as the move itself is unconstitutional and illegitimate."

This comes as the National Assembly, where the main opposition Democratic Party of Korea lawmakers hold 175 out of 300 parliamentary seats, is looking to float a motion to impeach the conservative president, who served less than half of his five-year term.

For this, the National Assembly's Judiciary Committee approved the plan on July 9 to hold two rounds of hearings, on Friday and on July 26. The ruling People Power Party lawmakers who comprise a minority of the committee walked out in protest in the process.

Kim and her mother Choi Eun-soon were among the figures to be summoned as witnesses on July 26, according to the Judiciary Committee.

On Friday, five Democratic Party lawmakers including the committee's vice chair Rep. Kim Seung-won, as well as Rep. Park Eun-jung of the minor opposition Rebuilding Korea Party, were denied entry to the presidential office in Seoul as they had attempted to submit a written request to summon witnesses.

Under the Act on Testimony and Appraisal before the National Assembly, a written request for witnesses must be served and delivered seven days before the date on which the witnesses shall attend. On July 19, seven presidential office secretaries are to attend the parliamentary hearing as witnesses. There are 39 witnesses in total that the committee looks to summon in the two rounds of hearings.

Liberal lawmakers on Monday filed a complaint with the independent investigative body Corruption Investigation Office for High-Ranking Officials against 10 presidential office secretaries including Chief of Staff Chung Jin-suk for illegally blocking the liberal lawmakers' attempt to submit the summon request.

According to Rebuilding Korea Party lawmaker Park's office, the lawmakers are considering other options than visiting the presidential office in Seoul to serve the written request calling for first lady Kim's attendance, including a publication of the fact in a newspaper.

The committee's move was motivated by a petition by an unidentified author on June 20 on the National Assembly's web portal, as the petition calling for Yoon's impeachment collected over 1.4 million signatures -- way more than the minimum threshold of 50,000 for a legislative step to initiate -- as of Monday.

The Yoon family's "corruption" allegations were among the five reasons the author claimed Yoon deserves impeachment. Kim had allegedly violated the antigraft law by accepting a luxury Dior bag valued at 3 million won ($2,170) last year. She is also allegedly involved in stock price manipulation since the early 2010s.

First lady Kim's close aide, surnamed Yoo, reportedly claimed that Kim had ordered the return of the luxury bag on the same day it was given, during a prosecution's interrogation at the Seoul Central District Prosecutors' Office earlier in July.

Yoon's approval rating, meanwhile, stood at the low-30 percent range for three months, according to Realmeter's polls. Yoon returned to Seoul Friday after a five-day trip to the United States to attend the North Atlantic Treaty Organization's summit.