South Korean lawmakers grilled former presidential officials and medical experts on the fourth day of a parliamentary corruption hearing as they dug into the alleged inaction of President Park Geun-hye at the time of a deadly ferry disaster in 2014.

The presidential office argued that Park was updated with written reports on April 16, 2014, when the Sewol ferry sunk, killing more than 300, mostly high school students.

But it has yet to clarify what exactly the president was doing, failing to squelch rumors that she received medical treatments, placenta injections or hair services during the critical hours.

During the hearing, opposition lawmakers came up with fresh materials to back up the allegations, which witnesses continued to deny.

Rep. Kim Han-jung of the main opposition Democratic Party said Park is suspected of receiving injections, unveiling photos before and after the ferry tragedy. One photo taken in May 2014 showed Park had bruises on her face.

Another lawmaker from the party claimed such injections were given even on the day of the sinking.

Medical doctors close to the president and her confidante Choi Soon-sil, a key suspect in the scandal, denied they carried out such operations on the day.

The witnesses present at the session included Kim Young-jae and

Cha Kwang-yul, who run hospitals regularly visited by Choi.

Kim said the bruises seemed to be made from shots, but that he

was not responsible for them. He said he was tending to his own

private matter during the so-called missing seven hours, ruling out

the possibility that he provided treatments to the president on

that day.

Kim Young-jae, however, said he did visit the presidential

office on several occasions to provide Park with skin treatments.

He added former presidential doctor Lee Byung-seok introduced him

to Choi.

Shin Bo-ra, who formerly served as a nurse officer at the

Presidential Security Service, told the committee that she was not

aware of the bruises. Shin also said she only delivered mouthwash

and eye drops to the president on the day of the sinking.

Park was impeached last week by the National Assembly. The

opposition parties cited her failure to fulfill her constitutional

duty as president to protect the lives of the people as a major

reason for the impeachment.

Of the 16 summoned figures who are presumed to hold keys to the

truth about "the missing seven hours," 13 appeared before the

special committee. Three key figures, including nurse officer Cho

Yeo-ok, did not show up, citing personal reasons.

Cho, who currently resides in the United States, is likely to

appear at the National Assembly next week, the defense ministry

said.

The panel issued orders of accompaniment for the remaining two

witnesses, both presidential officials, who are believed to be well

aware of the schedules of both Park and Choi. The order is issued

to force a suspect or witness to appear at a hearing when he or she

refuses to attend without a justifiable reason.

One of the major targets during the session was Kim Sang-man,

who worked as the medical advisor to the president.

He was earlier investigated by the prosecutors for prescribing

placenta injections for Park under Choi's name. The former advisor

also admitted to giving medical treatments to Park even before

being designated as the medical advisor.

The former medical advisor, however, said he did not go to the

presidential office on the day of the sinking.

Kim Sang-man added Choi asked him to issue her a prescription

to counter panic disorders before the confidante returned home from

Germany for investigation. The committee said the request was made

in an apparent bid to avoid the prosecutors' probe.

The committee said it will conduct an on-site investigation

into the presidential security office on Friday.

The presidential office, however, rejected the plan, citing

concerns about the possible leak of confidential information.

During the two previous sessions last week, the parliament

committee questioned business tycoons and Park's confidante Choi

Soon-sil's key acquaintances.

The committee will hold a fourth inquiry session on Thursday

focusing on Choi's daughter Chung Yoo-ra. The former member of the

national equestrian team was accused of receiving unlawful favors

from her high school and university under her mother's influence.

Chung Yun-hoi, Park's former secretary and ex-husband of Choi,

was also summoned for questioning, although he did not yet express

an intention to show up for the session. (Yonhap)