Rev. Moon Sun-myung, founder of the controversial Unification Church, is in critical condition with breathing problems, doctors said Wednesday.
He was taken into intensive care at the Catholic University's St. Mary's Hospital in Seoul on Monday.
"I understand that he is in critical condition after being admitted to the pulmonology division at the hospital," said the official, declining to be named.
Moon founded the Unification Church in Korea in 1952 and has built it into a worldwide religious organization claiming up to 7 million believers.
It is famed for mass weddings, which it has trumpeted as "dedicated to the creation of a peaceful world beyond borders and races."
Moon had picked spouses and presided over the ceremonies. The church extols Moon as the "True Parent of Mankind" and "the King of all Kings."
Born in Jeongju, North Pyeongan Province in North Korea in 1920, Moon has carried out activities for the reunification of Korea and democracy and freedom across the world.
Moon is also a conservative media mogul. His church runs the U.S.-based Washington Times and the Segye Times in Korea.