South Korea's Justice Minister Choo Mi-ae has ordered the prosecution to seek her approval before establishing a special investigative body outside its organization.

The Justice Ministry said Choo on Friday also gave specific instruction for the state investigative agency to set up special units only when deemed urgent or inevitable.

The ministry explained the move was in line with the reform drive to limit the prosecution's direct investigative authority, adding that related laws and regulations don't allow the chief prosecutor to set up such units without approval.

There is speculation, however, that the ministry is attempting to weaken the prosecutor general's discretionary power.

The prosecution is currently operating a special team to reinvestigate the 2014 Sewol ferry sinking that claimed more than 300 lives in an effort to determine the exact cause of the nation's worst maritime disaster.