Former President Moon Jae-in visited main opposition Democratic Party chair Lee Jae-myung in the hospital on Tuesday.
Moon is said to have urged Lee to stop his hunger strike, which entered its 20th day.
Within the party, attention is growing on whether the former president’s visit will provide a breakthrough in Lee’s strike.
Moon had earlier called the DP chair over the phone on the second day of his hunger strike on September 1, and had expressed concerns about Lee’s protest and had urged the party chair to take care of his health.
Lee was admitted to the Green Hospital in eastern Seoul on Monday after he was initially transported to a hospital nearby the National Assembly earlier in the day upon suffering a sudden drop in blood sugar level.
Tuesday marked the first time Moon visited Seoul since he stepped down from the top office last May.
After visiting Lee, Moon plans to attend a ceremony marking the fifth anniversary of the September 19 inter-Korean military agreement, an annex to the Pyongyang Joint Declaration of September 2018.