Indoor masking will be phased out gradually, Korean public health authorities said Friday, with the mask mandate to be downgraded to a recommendation as long as certain conditions are met.

The Central Disaster and Safety Countermeasures Headquarters did not specify when the phase-out would be implemented or any timeline for the measures.

In the first stage of the phase-out, indoor masks will be encouraged to be worn voluntarily. The mask mandate will remain intact on public transportation and at certain facilities with vulnerable groups, such as medical institutions, pharmacies and some social welfare facilities.

This first phase-out will be launched when two out of four conditions are satisfied. Those two include a stabilization of new cases, the reduction in number of critically ill patients and deaths, stable medical capabilities and high-risk groups acquiring immunity.

The second and final phase-out, under which the indoor mask mandate will be lifted at all places, will be launched when the current "serious" COVID-19 crisis stage is lowered to a level of "caution" or when the COVID-19 legal infectious disease level is adjusted from the current level 2 to level 4.

The authorities warned that the mask mandate can be reinstated if the situation changes due to new mutations or changes in overseas situations.

"Even when the obligation to wear an indoor mask is adjusted in the future, the protection effect and necessity of wearing a mask will not disappear. If necessary, please make quarantine rules a part of your life, such as voluntarily wearing a mask," KCDC head Jee Young-mee said at a briefing Friday.

The seven-day quarantine period for COVID-19 patients, however, will not be reduced.

"I think the seven-day quarantine obligation will be appropriate at the current stage," Jee said.

The ruling People Power Party earlier urged the government to consider reducing the quarantine period to three days.