They were forced to do household chores under inhumane conditions, according to the Center for Military Human Rights Korea, which cited multiple tip-offs from former and current service members.

A soldier was ordered to wear an electronic bracelet to vibrate whenever Park's family members call him inside the two-story official residence, the center said.

A soldier even attempted suicide in 2015 due to stress from the extreme demands from Park and his wife. Allegations of their human rights violations go on.

Park offered to be discharged earlier this week, saying he will take the responsibility for brewing public criticism. He did not confirm nor deny the allegations in a text message distributed to reporters, however.

"Starting today, the Army is conducting an on-site probe into how the official residence soldier system is operated," the official said. "It is expected to take about one week."

More than 100 soldiers are on duty at some 90 residential compounds of Army commanders nationwide.

The Army plans to announce the results of a separate investigation into the Park case and the level of punishment later in the day.

All able-bodied South Korean male adults are obliged to serve in the military for about two years. (Yonhap)